The North American Slime-Moulds.

by Thomas H. (Thomas Huston) MacBride.

PREFACE TO THE FIRST EDITION[1]

The present work has grown out of a monograph ent.i.tled _Myxomycetes of Eastern Iowa_, published by the present author about eight years ago.

The original work was intended chiefly for the use of the author's own pupils; but interest in the subject proved much wider than had been supposed, and a rather large edition of that little work was speedily exhausted. At that time literature on the subject in question--literature accessible to English readers--was scant indeed.

Cooke's translation of Rostafinski, in so far as concerned the species of Great Britain, was practically all there was to be consulted in English.

In 1892 appeared in London Ma.s.see's _Monograph of the Myxogastres_, and two years later in the same world's centre the trustees of the British Museum brought out Lister's _Mycetozoa_. Although these two English works both claim revision of the entire group under discussion, the latter paying special attention to American forms, nevertheless there still seems place for a less pretentious volume which for American students shall present succinct descriptions of North American species only. The material basis of the present work consists of collections now in the herbarium of the State University of Iowa. In acc.u.mulating the material the author has had the generous a.s.sistance of botanists in all parts of the country, from Alaska to Panama, and the geographical distribution is in most cases authenticated by specimens from the localities named. The descriptions, in case of species represented in Europe, are based upon those of European authors; for forms first described in this country, the original descriptions have been consulted. A bibliography follows this preface.

In reference to the omnipresent vexed question of nomenclature, a word is perhaps necessary. De Candolle's rule, "The first authentic specific name published under the genus in which the species now stands," may be true philosophy, but it is certainly an open question how that rule shall be applied. If an author recognized and defined a given species in times past, and, in accordance with views then held, a.s.signed the species to a particular genus, common honesty, it would seem, would require that his work be recognized. To a.s.sume that any later writer who may choose to set to familiar genera limits unknown before shall thereby be empowered to write all species so displaced his own, as if, forsooth, now for the first time in the history of science published or described, is not only absolutely and inexcusably misleading, but actually increases by just so much the amount of _debris_ with which the taxonomy of the subject is already c.u.mbered.

In face of a work so painstaking and voluminous as that of Rostafinski, and in view of the almost universal confusion that preceded him, it would seem idle to change for reasons purely technical the nomenclature which the Polish author has established. Especially is this true in the case of organisms so very perishable and fragile as those now in question where comparative revision is apt to result in uncertainty. We had preferred to leave the Rostafinskian, _i. e._ the heretofore current nomenclature, untouched; but since other writers have preferred to do otherwise, we are compelled to recognize the resultant confusion.

Slime-moulds have long attracted the attention of the student of nature.

For nearly two hundred years they find place more or less definite in botanical literature. Micheli, 1729, figures a number of them, some so accurately that the ident.i.ty of the species is hardly to be questioned.

Other early writers are Buxbaum and Dillenius. But the great names before Rostafinski are Schrader, Persoon, and Fries. Schrader's judgment was especially clear. In his _Nova Genera_, 1797, he recognizes plainly the difference between slime-moulds and everything else that pa.s.sed by the name of fungus, and proposed that they should be set off in a family by themselves,[2] but he suggested no definite name. Nees (C. G.) also made the same observation in 1817, and proposed the name _aerogastres_; but he cites as type of his aerogastres, _Eurotium_, and includes so many fungi, that it seems unsafe now to approve his nomenclature.

Schrader also has left an excellent account of the cribrarias, the basis of all that has since been attempted in that genus.

Persoon, in his _Synopsis_, 1801, attempts a review of all the fungi known up to that time. His notes and synonymy are invaluable, enabling us to understand the references of many of the earlier authors where these had otherwise been indefinite if not unintelligible. He makes a great many changes in nomenclature, and excuses himself on the ground that he follows, in this particular, ill.u.s.trious examples!

Unfortunately, so do we all!

Fries, in his _Systema Mycologic.u.m_, 1829, summed up in most wonderful way the work of all his predecessors and the mycologic science of his time. In reading Fries the modern student hardly knows which most to admire, the author's far-reaching, patient research, the singular ac.u.men of his taxonomic instinct, the graceful exactness of the Latin in which his conclusions are expressed, or the delicate courtesy with which he touches the work even the most primitive, of those his predecessors or contemporaries. Nevertheless in our particular group even the determinations of Fries are not conclusive. He himself often confesses as much. The microscopic technique of that day did not yield the data needful for minute comparison among these most delicate forms.

It remained for DeBary and Rostafinski to introduce a new factor into the description of species, and by spore-measurement and the delineation of microscopic detail to supply an element of definiteness which has no parallel in the work of any earlier student of this group. Under these conditions the revision undertaken by Rostafinski was of a most heroic sort. His work was almost a new beginning; and while in nomenclature he was inclined to follow the Paris Code, yet the inadequacy of the earlier descriptions often made such a course impracticable. The synonymy of Rostafinski is largely that of Fries, and upon this the Polish author attempts to apply the law of priority. In the historical note, _wzmianka historyczna_, accompanying the description of each specific form, he generally states the reason for the nomenclature he adopts, whether selected from the ma.s.s of supposed synonymy or introduced by himself _de novo_. Unfortunately, Rostafinski is sometimes purely arbitrary in his selections. He sometimes changes a specific or even generic name, otherwise correctly applied, simply because in primary etymological significance the name seems to him inappropriate. In such cases it is proper to restore the earlier name. Nevertheless Rostafinski is still our most trustworthy guide.

Of course, where later investigations have served to obliterate the once-thought patent distinctions between supposed genera or species, it is proper to unite such forms under the older determinable t.i.tles and this we have attempted. But wherever in the present work a name has been changed, the name of the earlier author will be found in parenthesis, followed immediately by that of him who made the change, and in general, recent practice, especially as expressed in the rules of the various codes, has determined the puzzling questions of nomenclature.

In justification of the use of _Myxomycetes_ as a general t.i.tle it may be said that in this case prevalent usage is not inconsistent with a rational application of the rules of priority. The Friesian designation _Myxogastres_ was applied by its author in 1829 to the endosporous slime-moulds as a section of gasteromycetous fungi. Four years later Link, perceiving more clearly the absolute distinctness of the group, subst.i.tuted the name _Myxomycetes_. In the same year Wallroth adopted the same designation, but strangely confused the limitations of the group he named. Wallroth seems to have thought _Myxomycetes_ a synonym for _Gasteromycetes_ Fries. In 1858 DeBary applied the t.i.tle _Mycetozoa_ to a group which included the then lately discovered _Acrasieae_ with the true slime-moulds, both endosporous and exosporous. For all except the _Acrasieae_ DeBary retained the old appellation, Myxomycetes.

Rostafinski adopted DeBary's general name, but changed its application.

As it has been shown, since DeBary's time, that the _Acrasieae_[3] have no true plasmodium, and are therefore not properly, or at least not necessarily, a.s.sociated with the slime-moulds, there appears no necessity for the term _Mycetozoa_, and the question lies between _Myxogastres_ and _Myxomycetes_. Of these two names the former, as we have seen, has undoubted priority, but only as applied to the endosporous species. The same thing was true of Link's designation until DeBary redefined it, but having been taken up by DeBary, redefined and correctly applied, Myxomycetes (Link) DeBary must remain the undisputed t.i.tle for all true slime-moulds, endosporous and exosporous alike.

In arranging the larger divisions of the group the scheme of Rostafinski has been somewhat modified in order to give expression to what the present author deems a more natural sequence of species. The highest expression of myxomycetan fructification is doubtless the isolated sporangium with its capillitium. This is reached by successive differentiations from the simple plasmodium. The aethalium may be esteemed in some instances a case of degeneration, in others of arrested development. In any event in the present arrangement, aethalioid forms are first disposed of, leaving the sporangiate species to follow from plasmodiocarpous as directly as may be.

The artificial keys herewith presented proceed on the same plan and are to be taken, as such keys always are, not as definitive in any case, but simply as an aid to help the student more speedily to reach a probably satisfactory description.

FOOTNOTES:

[1] _The North American Slime Moulds_, 1899.

[2] Schrader, _Nova Plantarum Genera_, 1797, pp. vi-vii.

[3] Cf. Edgar W. Olive, _Monograph of the Acrasieae_; Boston, 1902.

PREFACE TO THE SECOND EDITION

The first edition of this little book having been exhausted long ago, the writer in this second issue takes opportunity to correct sundry errata, typographical and other, and at the same time to incorporate such new information in reference to individual species and to the subject entire as the researches of more recent years may afford.

To Miss Gulielma Lister, of London, the writer expresses his sense of deep obligation for much a.s.sistance in settling difficult matters of nomenclature and identification; it will be found as a result that in most instances the same thing in the two volumes, English and American, appears under the same name. There are still differences; these result in most cases from different points of view, different estimates or emphasis of characteristics in these ever elusive objects.

To Professor Torrend, formerly of Lisbon, the writer is indebted for a set of European types, and to Professor Bethel, pathologist of Denver, for rich material from the fertile mountains of Colorado and California.

To Professor Morton Peck, of Oregon, we are indebted for many notes of the color of plasmodia and for collections of Pacific coast forms. Mr.

Bilgram, of Philadelphia, read the ma.n.u.script of the genus _Physarum_ and has contributed many rare species. To Dr. Sturgis, of Ma.s.sachusetts, we are indebted for material from both east and west.

The present volume is intended especially for American readers and is accordingly particularly devoted to a discussion of species so far reported on the western continent; nevertheless it has seemed wise to include a brief description of some other forms as well, and reference to many extra-limital species now generally recognized will be found here and there in connection with the more extended treatment of related American forms.

_February twenty-eight, 1921._

At the last moment, nearly all plates and drawings of the first edition disappeared! necessitating a quick renewal of drawings and plates. This may in part explain lack of uniformity, and various minor irregularities sure to grieve the intelligent student.

BIBLIOGRAPHY

The following are the princ.i.p.al works consulted in the prosecution of the investigations here recorded:--

1763. Adanson, M. Familles des Plantes.

1805. Albertini--see under Schweinitz.

1841. Annals and Magazine of Natural History. London, various volumes: 1841, Ser. I., vol. vi.; 1850, Ser. II., vol. v.

1887. Annals of Botany, vols. i-x.x.xi.

1783. Batsch, A. J. G. C. Elenchus Fungorum; with Continuatio I. 1786; Continuatio II. 1789.

1775. Battara, A. Fungorum Agri Arimensis Historia.

1860. Berkeley, M. J. Outlines of Fungology.

1789. Bolton, J. History of Funguses about Halifax.

1851. Bonorden, H. F. Mycologie.

1875. Botanical Gazette, The. Various volumes to 1921.

1843. Botanische Zeitung. Various volumes to 1898.

1892. Bulletin Laboratories Nat. Hist. Iowa, vol. ii.