Much of the nitrogen is present in the form of non-proteid substances of a very low food value. Another and very considerable portion enters into the composition of a substance closely related to cellulose. A third source of error was the a.s.sumption that all the proteid material was digestible. It is now known that a very considerable portion is not digestible and hence not available as food. Thus, notwithstanding the 5.79 per cent. of nitrogen in _Coprinus comatus_, we find but .82 per cent. in the form of actually available (i. e., digestible) proteids, or approximately one-seventh of what was formerly supposed to be present.

The digestibility of the proteids varies very greatly with the species.

Morner found the common field mushroom, _Agaricus campestris_, to have a larger amount of proteids available than any other species studied by him. Unfortunately, the digestibility of the American plant has not been tested. There is great need for further work along this line. Enough has been done, however, to demonstrate that mushrooms are no longer to be regarded as a food of the proteid cla.s.s.

The energy for the muscular exertion and heat is most economically derived from the foods in which the carbohydrates and fats predominate.

The common way of comparing foods of the first two cla.s.ses scientifically is to compare their heat-giving powers. The unit of measurement is termed a _calorie_. It represents the amount of heat required to raise a kilogram of water 1 Centigrade. (This is approximately the heat required to raise one pound of water 4 Fahrenheit.) A man at moderately hard muscular labor requires daily enough food to give about 3500 _calories_ of heat-units. The major part of this food may be most economically derived from the foods of the second cla.s.s, any deficiency in the .28 lb. of digestible protein being made up by the addition of some food rich in this substance.

In the following table the value of ten pounds of several food substances of the three cla.s.ses has been worked out. Especial attention is called to the column headed "proteids" and to the last column where the number of heat-units which may be purchased for one cent at current market rates has been worked out.

TABLE II.

NUTRITIVE VALUE OF TEN POUNDS OF SEVERAL FOODS.

========================================================================+

PROTEIDS.

FATS.

CARBO-

CALORIES.

COST.

CALORIES

HYDRATES.

FOR ONE

CENT.

------------------------------------------------------------------------

a. {Beef (round)

1.87

.88

----

7200

$1.50

48.

{Beans (dried)

2.23

.18

5.91

15900

.30

530.

b. {Cabbage

.18

.03

.49

1400

.15

93.

{Potatoes

.18

.01

1.53

3250

.10

325.

{Flour (roller

1.13

.11

7.46

16450

.25

658.

process)

c. {Coprinus comatus

.04

.025

.434

987

2.50

3.9

{Pleurotus

.051

.042

.828

1811

2.50

7.2

ostreatus

{Morch.e.l.la

.094

.05

.306

955

2.50

3.8

esculenta

{Agaricus

.18

.03

.46

1316

2.50

5.3

campestris

{Oysters

.61

.14

.33

2350

2.00

11.7

========================================================================+

The mushrooms have been valued at 25 cents per pound, which is probably considerably below the average market price for a good article. It should also be remarked that the amounts given in this table are the digestible and hence available const.i.tuents of the foods. The only exception to this is in the case of the fats and carbohydrates of the mushrooms, no digestion experiments having been reported on these const.i.tuents. In the absence of data we have a.s.sumed that they were entirely digested.

The beef and beans are typical animal and vegetable foods of the proteid cla.s.s. A glance at the table will show how markedly they differ from the mushrooms. The latter are nearest the cabbage in composition and nutritive value. The similarity between the cabbage and the _Agaricus campestris_ here a.n.a.lyzed is very striking. The potato is somewhat poorer in fat, but very much richer than the mushroom in carbohydrates.

The figures in the last column will vary of course with fluctuations in the market price, but such variation will not interfere at any time with the demonstration that _purchased_ mushrooms are not a poor man's food.

Here we find that one cent invested in cabbage at 1-1/2 cents per pound, gives 93 _calories_ of nutrition, while the same amount invested in _Agaricus campestris_--the common mushroom of our markets--would give but 5.3 _calories_, although they are almost identical so far as nutritive value is concerned.

The same sum invested in wheat flour, with its high carbohydrate and good proteid content, would yield 658 _calories_ or one-sixth the amount necessary to sustain a man at work for one day. The amount of mushrooms necessary for the same result is a matter of simple computation.

Mushrooms, however, have a distinct and very great value as a food of the third cla.s.s, that is, as condiments or food accessories, and their value as such is beyond the computation of the chemist or the physiologist, and doubtless varies with different individuals. They are among the most appetizing of table delicacies and add greatly to the palatability of many foods when cooked with them. It is surely as unfair to decry the mushroom on account of its low nutritive value, as it is wrong to attribute to it qualities which are nothing short of absurd in view of its composition. In some respects its place as a food is not unlike that of the oyster, celery, berries, and other delicacies. Worked out on the basis of nutritive value alone they would all be condemned; the oyster for instance presents a showing but little better than the mushroom, and vastly inferior, so far as economy is concerned, to the common potato. This, too, for oysters purchased by the quart. The nutritive value of one cent's worth of oysters "on the half sh.e.l.l" would be interesting!

The question of the toxicology of the higher fungi is one of very great theoretical and practical interest. But on account of the great difficulties in the way of such investigations comparatively little has yet been accomplished. A few toxic compounds belonging chiefly to the cla.s.s termed alkaloids have, however, been definitely isolated.

=Choline.=--This alkaloid is of wide occurrence in the animal and vegetable kingdoms. It has been isolated from _Amanita muscaria_, _A.

pantherina_, _Boletus luridus_, and _Helvella esculenta_. It is not very toxic, but on uniting with oxygen it pa.s.ses over to muscarine. According to Kobert the substance formed from choline on the decay of the mushrooms containing it is not muscarine, but a very closely related alkaloid, _neurin_. This transformation of a comparatively harmless alkaloid to an extremely deadly one simply by the partial decay of the plant in which the former is normally found, emphasizes very much the wisdom of rejecting for table use all specimens which are not entirely fresh. This advice applies to all kinds of mushrooms, and to worm-eaten and otherwise injured, as well as decayed ones. Neurin is almost identical in its physiological effects with muscarine, which is described below.

=Muscarine.=--This is the most important because the most dangerous alkaloid found in the mushrooms. It is most abundant in _Amanita muscaria_, it is also found in considerable quant.i.ty in _Amanita pantherina_, and to a lesser, but still very dangerous extent in _Boletus luridus_ and _Russula emetica_. It is quite probably identical with bulbosine, isolated from _Amanita phalloides_ by Boudier.

_Muscarine_ is an extremely violent poison, .003 to .005 of a gram (.06 grain) being a very dangerous dose for a man. Like other const.i.tuents of mushrooms, the amount of muscarine present varies very greatly with varying conditions of soil and climate. This, indeed, may account for the fact that _Boletus luridus_ is regarded as an edible mushroom in certain parts of Europe, the environment being such that little or no muscarine is developed.

According to Kobert, _Amanita muscaria_ contains, besides choline and muscarine, a third alkaloid, _pilz-atropin_. This alkaloid, like ordinary atropin, neutralizes to a greater or less extent the muscarine.

The amount of pilz-atropin present varies, as other const.i.tuents of mushrooms vary, with varying conditions of soil, climate, etc., and it may be that in those localities where the _Amanita muscaria_ is used for food the conditions are favorable for a large production of pilz-atropin which neutralizes the muscarine, thus making the plant harmless. Be this as it may, _Amanita muscaria_, so deadly as ordinarily found, is undoubtedly used quite largely as food in parts of France and Russia, and it has been eaten repeatedly in certain localities in this country without harm.

Fortunately muscarine has a very unpleasant taste. It is interesting in this connection to note that the _Amanita muscaria_ is said to be used by the inhabitants of Northern Russia--particularly the Koraks--as a means of inducing intoxication. To overcome the extremely unpleasant taste of the plant they swallow pieces of the dried cap without chewing them, or boil them in water and drink the decoction with other substances which disguise the taste.

The symptoms of poisoning with muscarine are not at once evident, as is the case with several of the less virulent poisons. They usually appear in from one-half to two hours. For the symptoms in detail we shall quote from Mr. V. K. Chestnut, Dept. of Agr., Washington (Circular No. 13, Div. of Bot.): "Vomiting and diarrhoea almost always occur, with a p.r.o.nounced flow of saliva, suppression of the urine, and various cerebral phenomena beginning with giddiness, loss of confidence in one's ability to make ordinary movements, and derangements of vision. This is succeeded by stupor, cold sweats, and a very marked weakening of the heart's action. In case of rapid recovery the stupor is short and usually marked with mild delirium. In fatal cases the stupor continues from one to two or three days, and death at last ensues from the gradual weakening and final stoppage of the heart's action."

The treatment for poisoning by muscarine consists primarily in removing the unabsorbed portion of the mushroom from the alimentary ca.n.a.l and in counteracting the effect of muscarine on the heart. The action of this organ should be fortified at once by the subcutaneous injection, by a physician, of atropine in doses of from one one-hundredth to one-fiftieth of a grain. The strongest emetics, such as sulphate of zinc or apomorphine, should be used, though in case of profound stupor even these may not produce the desired action. Freshly ignited charcoal or two grains of a one per cent. alkaline solution of permanganate of potash may then be administered, in order, in the case of the former substance, to absorb the poison, or, in the case of the latter, to decompose it. This should be followed by oils or oleaginous purgatives, and the intestines should be cleaned and washed out with an enema of warm water and turpentine.

Experiments on animals poisoned by _Amanita muscaria_ and with pure muscarine show very clearly that when the heart has nearly ceased to beat it may be stimulated to strong action almost instantly by the use of atropine. Its use as thus demonstrated has been the means of saving numerous lives. We have in this alkaloid an almost perfect physiological antidote for muscarine, and therefore in such cases of poisoning its use should be pushed as heroically as the symptoms of the case will warrant.

The presence of phallin in _Amanita muscaria_ is possible, and its symptoms should be looked for in the red color of the blood serum discharged from the intestines.

=Phallin.=--The exact chemical nature of this extremely toxic substance is not certainly known, but it is generally conceded to be of an alb.u.minous nature. That it is an extremely deadly poison is shown by the fact that .0015 grain per 2 lbs. weight of the animal is a fatal dose for cats and dogs. It is the active principle of the most deadly of all mushrooms, the _Amanita phalloides_, or death-cup fungus. We quote again from Mr. Chestnut's account of phallin and its treatment: "The fundamental injury is not due, as in the case of muscarine, to a paralysis of the nerves controlling the action of the heart, but to a direct effect on the blood corpuscles. These are quickly dissolved by phallin, the blood serum escaping from the blood vessels into the alimentary ca.n.a.l, and the whole system being rapidly drained of its vitality. No bad taste warns the victim, nor do the preliminary symptoms begin until nine to fourteen hours after the poisonous mushrooms are eaten. There is then considerable abdominal pain and there may be cramps in the legs and other nervous phenomena, such as convulsions, and even lockjaw or other kinds of tetanic spasms. The pulse is weak, the abdominal pain is rapidly followed by nausea, vomiting, and extreme diarrhoea, the intestinal discharges a.s.suming the 'rice-water'

condition characteristic of cholera. The latter symptoms are persistently maintained, generally without loss of consciousness, until death ensues, which happens in from two to four days. There is no known antidote by which the effects of phallin can be counteracted. The undigested material, if not already vomited, should, however, be removed from the stomach and intestines by methods similar to those given for cases of poisoning by _Amanita muscaria_.

"After that the remainder of the poison, if the amount of phallin already taken up by the system is not too large, may wear itself out on the blood and the patient may recover. It is suggested that this wearing-out process may be a.s.sisted by transfusing into the veins blood freshly taken from some warm-blooded animal. The depletion of the blood serum might be remedied by similar transfusions of salt and warm water."

=Helvellic Acid.=--This very deadly poison is sometimes found in _Helvella esculenta_ Persoon (Gyromitra esculenta), particularly in old or decaying specimens. It has been studied and named by Boehm. It is quite soluble in hot water, and in some localities this species of _Helvella_ is always parboiled--the water being thrown away--before it is prepared for the table. It seems to be quite generally agreed that young and perfectly fresh specimens are free from the poison. As the poison is very violent, however, this plant should be carefully avoided.

The symptoms resemble in a very marked degree those of the deadly phallin, the dissolution of the red corpuscles of the blood being one of the most marked and most dangerous; this is accompanied by nausea, vomiting, jaundice, and stoppage of the kidneys. There is no known antidote for this poison, hence the little that can be done would be similar to that mentioned under phallin.

When poisoning by mushrooms is suspected, one cannot too strongly urge that the services of a competent physician should be secured with the least possible delay.

CHAPTER XXIII.

DESCRIPTION OF TERMS APPLIED TO CERTAIN STRUCTURAL CHARACTERS OF MUSHROOMS.

By H. Ha.s.sELBRING.

In fungi, as in higher plants, each organ or part of the plant is subject to a great number of variations which appeal to the eye of the student, and by which he recognizes relationship among the various individuals, species, and genera of this group. For the purpose of systematic studies of mushrooms or even for the recognition of a few species, it is of primary importance to be acquainted with terms used in describing different types of variation. Only a few of the more important terms, such as are employed in this book, together with diagrams ill.u.s.trating typical cases to which they are applied, will be given here.

=The pileus.=--The _pileus_ or _cap_ is the first part of a mushroom which attracts the attention of the collector. It is the fleshy fruit body of the plant. This, like all other parts of the mushroom, is made up, not of cellular tissue as we find it in flowering plants, but of numerous interwoven threads, called _hyphae_, which const.i.tute the flesh or _trama_ of the pileus. Ordinarily, the filamentous structure of the flesh is very obvious when a thin section of the cap is examined under the microscope, but in certain genera, as _Russula_ and _Lactarius_, many branches of the _hyphae_ become greatly enlarged, forming little vesicles or bladders. These vesicles lie in groups all through the flesh of the pileus, sometimes forming the greater part of its substance. The filamentous _hyphae_ pa.s.s around and through these groups, filling up the interstices. In cross section this tissue resembles parenchyma, and appears as if it were made up of rounded cells. Such a trama is said to be _vesiculose_ to distinguish it from the ordinary or _floccose_ trama.

The threads on the outer surface of the pileus const.i.tute the cortex or cuticle. They are thick walled and often contain coloring matter which gives the plants their characteristic color. In many species their walls become gelatinized, covering the outside of the pileus with a viscid, slimy, or glutinous layer, often called _pellicle_. In other instances the corticle layer ceases to grow with the pileus. It is then torn and split by the continued expanding of the rest of the plant, and remains on the surface in the form of hairs, fibers, scales, etc.

[Ill.u.s.tration: FIGURE 239. Portion of vesiculose trama in the pileus of a Russula.]

[Ill.u.s.tration: FIGURE 240. Portion of a floccose trama.]

As an example of the most usual form of the pileus, we may take that of the common mushroom (_Agaricus campestris_) when it is nearly expanded.

The pileus is then quite regular in outline and evenly _convex_ (Fig.

243). Many mushrooms during the early stages of their development have this form, which is variously changed by later growth. The convex pileus usually becomes _plane_ or _expanded_ as it grows. If the convexity is greater it is said to be _campanulate_ (Fig. 245), _conical hemispherical_, etc., terms which need no explanation. The pileus is _umbilicate_ when it has an abrupt, sharp depression at the center (Fig.

241), _infundibuliform_ when the margin is much higher than the center, so that the cap resembles a funnel (Fig. 244), and _depressed_ when the center is less, or irregularly, sunken. When the center of the pileus is raised in the form of a boss or k.n.o.b it is _umbonate_ (Fig. 242). The umbo may have the form of a sharp elevation at the center, or it may be rounded or obtuse, occupying a larger part of the disc. When it is irregular or indistinct the pileus is said to be _gibbous_ (Fig. 246).

[Ill.u.s.tration: FIGURE 241. FIGURE 242. FIGURE 243.

FIGURE 241.--Omphalia campanella, pileus umbilicate, gills decurrent.

FIGURE 242.--Lepiota procera, pileus convex, umbonate; annulus free, movable; gills free.

FIGURE 243.--Agaricus campestris, pileus convex, gills free.]

=The gills.=--The _gills_ or _lamellae_ are thin blades on the under side of the pileus, radiating from the stem to the margin. When the pileus is cut in halves the general outline of the gills may be observed. In outline they may be broad, narrow, lanceolate, triangular, etc. In respect to their ends they are _attenuate_ when gradually narrowed to a sharp point, _acute_ when they end in a sharp angle, and _obtuse_ when the ends are rounded. Again, the gills are _arcuate_ when they arch from the stem to the edge of the pileus, and _ventricose_ when they are bellied out vertically toward the earth.

[Ill.u.s.tration: FIGURE 244.

c.l.i.tocybe infundibuliformis, pileus infundibuliform, gills decurrent.]

[Ill.u.s.tration: FIGURE 245.