But Lloyd adds, in speaking of the reports of various experts and ranchmen:

Their description concerning its toxic action on animals agreed, and it was folly to argue that so many observers from so many sections of the country could be misled. There must be an undetermined something behind the loco-weed.[131]

In 1893 O'Brine, from Colorado, and Mayo, from Kansas, reported on their work with the loco plants. O'Brine failed to isolate any alkaloidal or other poisonous body, and his feeding experiments on himself and on rabbits having failed, he sums up in despair: "The more I examine the loco question, the more I am persuaded that we must look for some other cause besides the loco-weed."[132] At the end of his report he gives some ash a.n.a.lyses but fails to interpret them. He also fails to give details as to the method of obtaining and estimating his ash. O'Brine's ash a.n.a.lyses are as follows:

KEY TO ASH a.n.a.lYSIS: A = SiO_{2}.

B = Fe_{2}O_{3} and Al_{2}O_{3}.

C = CaO.

D = MgO.

E = K_{2}O.

F = Na_{2}O.

G = H_{2}SO_{4} H = Cl.

I = P_{2}O_{5}.

J = CO_{2}

------+-----+-----+-----+-----+----+-----+----+----+----+----+-----+ Plant.

Total

ash.

A

B

C

D

E

F

G

H

I

J

------+-----+-----+-----+-----+----+-----+----+----+----+----+-----+ AM

12.15

32.77

16.26

6.05

3.11

13.30

3.21

3.9

0.47

6.12

10.55

AL

13.52

17.08

12.21

14.27

2.62

17.26

5.75

3.22

3.87

3.30

17.37

AC

12.36

7.82

5.97

12.10

3.55

23.35

3.38

5.56

9.0

4.67

20.62

------+-----+-----+-----+-----+----+-----+----+----+----+----+-----+ KEY TO PLANTS: AM = _Astragalus mollissimus_ (whole plant) AL = _Aragallus lamberti_ (whole plant) AS = _Astragalus caryocarpus_

These a.n.a.lyses are evidently incorrect, as...o...b..ine estimates a carbon content of 4.13 per cent for the first, and for the second 2.22 per cent, showing incomplete combustion.

Mayo[133] experimented with alcoholic and aqueous extracts of dried _Astragalus mollissimus_ on guinea pigs, with negative results, and was first led to deny a relationship between the disease and the plants.

Later, as a result of the post-mortem findings, he was convinced that his first conclusion was wrong and that "the disease is certainly the result of animals feeding upon the loco-weed." Mayo says:

A careful survey of the experiments performed and observations noted leads me to the opinion that the disease known as "loco" is the result of malnutrition, or a gradual starvation, caused by the animals eating the plants known as "loco weeds," either _Astragalus mollissimus_ or _Aragallus lamberti_. If there is a narcotic principle in the plant, chemists have failed to find it and a fluid extract does not possess it, and a ton of the plant eaten by an animal ought to contain enough of the poisonous properties to destroy an animal.

Kobert[134] has also tested the activity of _Astragalus mollissimus_ and says, "Ich fand _Astragalus mollissimus_ ziemlich unwirksam."

Doctor McEackran[135] fed dried _Astragalus mollissimus_ and _Aragallus lamberti_ mixed with feed to a stabled animal for two months without result. (Animal not stated).[136] Similar negative experiments are reported from the State of Washington, but the amounts used were too small to form any conclusions.[137]

Mr. V. K. Chesnut[138] has busied himself with the loco problem, but mainly in an executive capacity, his own efforts being directed to the study of the relation of the loco plants to the disease on the range. He has done no laboratory work. Chesnut and Wilc.o.x made numerous autopsies on sheep and experiments on animals. They claimed that an extract of _Aragallus spicatus_ produced some slight narcotic action in rabbits.

Their pathological examinations failed to show any characteristic lesion, but they state that the cerebral membranes were in all cases slightly congested. They deny any causative relationship to the presence of worms or with feeding upon alkalis. They believe that sheep are more likely to become locoed if not salted regularly. Chesnut describes one case in which a lamb became locoed by nursing from a locoed mother.

In 1901 Reid Hunt, at that time a special agent of the United States Department of Agriculture, studied the loco question in Montana, working mainly with _Aragallus spicatus_. He moistened the ground-up plant with 93 per cent ethyl alcohol and then percolated it until exhausted. This extract was evaporated and taken up with water so that 1 c.c. of the solution corresponded to 10 grams of the plant. This was fed to an active young rabbit weighing 490 grams, 6 c.c. being fed by the mouth and followed in about an hour by 10 c.c. more, and two hours after this by 15 c.c. This rabbit showed no symptoms during the following day. The next day it was very dull and there was marked muscular weakness, as the rabbit's legs were spread wide apart and his nose rested on the ground.

Later respiration became very slow and the pupils were dilated. The paralytic symptoms increased and finally, after a convulsive movement, the animal died, thirty-six hours after the first feeding. Hunt merely states of the post-mortem examination that the stomach was well filled and that the "walls seem normal."

Hunt tried to isolate an active principle by the Dragendorff method, but failed to obtain any physiologically active shakings. He tried hypodermic injections of 80 per cent alcohol extractions of the fresh green plant, and after the injection of an extract corresponding to 60 grams of the fresh plant there was no effect produced. He tried to induce symptoms by feeding the plant itself to rabbits, but was unsuccessful, as the rabbits refused to eat the plant. He was not able to induce symptoms with the extracts of the dried plant.[139]

Marshall[140] studied the loco question with regard to sheep and practically denies the existence of a locoed condition due to eating the loco plants, but believes the condition due to bad feeding, parasitism, etc. He lays great stress upon the presence of worms, but fails to see that they may be merely a secondary infection superimposed upon an already morbid condition produced by eating the plants. Others have claimed that the cause is an insect living upon the loco plants. Others, again, have suggested an a.n.a.logy with trypanosome disorders.

Chesnut has held the view that many of the cases of so-called locoed sheep were really due to parasites, but that there was a true locoed condition due to eating the loco weeds.

The lack of agreement in the results of the investigators has caused many to doubt any positive relation between the plant and the disease, and even as late as 1904 Payne[141] practically says these diseases are due to lack of nutrition and not to the loco plant. The matter has been summed up in a recent work as follows:

Though many chemists have sought for the const.i.tuents, none have been able to locate the active properties, the trace of alkaloids, resins, volatile and fixed oils having each in turn been found dest.i.tute of it. Yet the poisonous properties are fully established by field observations. The destructiveness of these plants to stock is so great as to have probably caused upward of a million dollars loss in the aggregate, and large bounties have been offered by State governments for an effective method of avoiding such losses.

It is considered very probable that the poisonous const.i.tuent is alb.u.minoidal.[142]

FOOTNOTES:

[83] Storke, B. F. The Loco Weed. Med. Current, vol. 8, p.

155. 1892.--Kellogg, A. California and Colorado "Loco"

Poisons. Cal. Acad. Sci. Proc. for 1875, vol. 6, p. 3. 1876.

NOTE.--The very early reports of these loco plants were purely botanical. See Torrey, J., Botany, in Report on the United States and Mexican Boundary Survey, by W. H. Emory, vol. 2, p. 56, 1859; also Botanical Register, London, vol.

13, pl. 1054, 1827.

[84] Vasey, G. Plants Poisonous to Cattle in California.

Rept. of Commissioner of Agriculture for 1874, p. 159. 1875.

[85] Vasey, G. Botanical Notes. Monthly Reports of Dept.

Agriculture for 1873, p. 503. 1874.

[86] Vasey, G. Botanical Notes. Monthly Reports of Dept.

Agriculture for 1874, p. 513. 1875.

[87] Brewer, W. H., and Watson, S. Geological Survey of California, Botany, vol. 1, p. 155. 1876.

[88] Rothrock, J. T. Notes on Economic Botany, in G. M.

Wheeler's Report upon U. S. Geographical Surveys West of the One Hundredth Meridian, vol. 6, p. 43. 1878.

[89] Kellogg, A. California and Colorado Loco Poisons. Cal.

Academy of Sciences, Proc., 1875, vol. 6, p. 3. 1876.

[90] Rothrock, J. T. Poisonous Properties of the Leguminosae.

Acad. of Nat. Sci., Phila., Proc., vol. 29, p. 274. 1877.

[91] Prescott, A. B. Laboratory Notes--A Partial a.n.a.lysis of the Oxytropis Lamberti. Amer. Journ. Pharm., vol. 50, p. 564.

1878.

[92] Rept. of Commissioner of Agriculture for 1878, p. 134.

1879.

[93] Rept. of Commissioner of Agriculture for 1879, pp. 89, 90. 1880.

[94] Rept. of Commissioner of Agriculture for 1886, p. 75.

1887. Rept. of Commissioner of Agriculture for 1884, p. 123.

1884.

[95] Rothrock, J. T. Notes on Economic Botany, in G. M.

Wheeler's Report upon U. S. Geographical Surveys West of the One Hundredth Meridian, vol. 6, p. 43. 1878.

[96] Gibbons, H. Poisonous Effects of Crotalaria--Vulgo Rattle Weed, Loco Weed. Pacific Med. and Surg. Journ., vol.

21, p. 496. 1878-79.

[97] Ott, I. Physiological Action of Astragalus Mollissimus.

New Remedies, vol. 11, p. 227. 1882.

[98] Hill, J. R. Note on a Species of Astragalus from Cyprus.