CHAPTER IV. — INTRODUCTION. 127 



Tulasne's doctrine of pleomorphy raised indeed a storm of controversy that lasted for 

 some time. On the one hand a conservative opposition was naturally to be expected 

 on the part of those who had already enquired into the species of Fungi, and had become 

 accustomed to find a species in every detached form with some kind of spore-formation, 

 disregarding entirely the question of the course of development and genetic connection. 

 The most aggressive representative of this conservative opposition was perhaps 

 Bonorden x ; others were more cautious and professed to be open to conviction. 



On the other hand a misunderstanding of the word pleomorphy led men of 

 enthusiastic character to extravagant conclusions. ' The explanation of all enigmatical 

 fungal forms has been reserved,' it was said, 'for our decade 2 ,' and the appearance of 

 two or more different fungal forms in the same spot close to each other, or one after 

 the other, was regarded at once as a case of pleomorphy of one species and proclaimed 

 as loudly as possible. Many experiments in culture were also undertaken, and here 

 too every thing that grew on the spot which had been purposely sown found its place 

 if possible in the cycle of whatever pleomorphous species the observer happened to 

 think of. If the character of the substratum was changed in such cultures, the fungal 

 forms that were obtained were often different ; nor could anything be more desired, 

 for the phenomenon of pleomorphy appeared now to have found its physiological 

 explanation in the effect of the various physical and chemical qualities of the substratum. 

 This gave rise to accounts such as the following : Saccharomyces Cerevisiae, the 

 Fungus of beer-yeast, grows in saccharine fluids in the form indicated by the name. 

 If it is eaten by flies it developes in them into the primordia of Entomophthora ; these 

 grow in the dead insects or moist substrata either into the form which bears the last 

 name (section XLVj or into Mucor (section XLI), but into Achlya (section XL) if the 

 flies fall into water. Finally Saccharomyces may again be formed from Mucor in 

 saccharine fluids, &c. &c. 3 Bail, Hoffmann, and especially Hallier, were the chief 

 representatives of these pleomorphistic extravagances. Others eager to share the 

 laurels of these discoverers modestly adopted their views. So far as these obser- 

 vations possess any historic interest in special cases they will be mentioned in 

 succeeding sections. Such of them as, like Hallier's especially, only belong to the 

 scientific chro?iiqtte scandaleuse will not be further noticed ; this course is justified by 

 a critical notice of these matters which appeared some time ago 4 . 



A critical examination of these pleomorphistic aberrations shows at once that the 

 different forms were not duly discriminated from one another, that no sufficient notice 

 was taken of the fact that several species are social and are in the habit of appearing 

 together, or of the possibility that one may take the place of another, or be developed 

 as a parasite on another, and that strange spores may come from without and mix with 

 the spores which it is desired to cultivate. It is true that an elaborate provision was 

 made of bell-jars, glass tubes, and similar appliances to prevent the last source of error. 

 But even admitting that the apparatus 'worked with absolute certainty,' it was 

 forgotten in using it that unbidden guests might be introduced into the apparatus 

 when the living objects were placed in it which were intended to be cultivated, and 

 that in fact it was scarcely possible to prevent their intrusion without a more complete 

 control of the conditions than is afforded by a non-microscopical apparatus. The 

 first requisite in a morphological investigation which is also an enquiry into the 

 history of development, namely the proof of the organic continuity necessarily 



1 Abhandl. aus d. Gebiete d. Mycologie, Halle, 1S64. — Zur Kenntn. einiger d. wichtigsten 

 Gattungen d. Coniomyceten u. Cryptomyceten, Halle, i860. 



2 Bot. Ztg. 1856, p. 799. 



3 Bail, Ueber Krankheiten d. Insecten durch Pilze (Ber. d. Vers. d. Naturforschcr zu Konigs- 

 berg) ; — Id. Die wichtigsten Satze d. neuern Mycologie (N. Act. Nat. Curios. 28). 



4 Jahresber. ii. d. Leistungen u. Fortschr. d. Medicin, herausgeg. v. Virchow u. Hirsch, Jahrg. 

 2, 1867, Bd. II, Abth. 1, pp. 240-252; reproduced in Bot. Ztg. 1868, p. 686. See also a clear historic 

 account by A. Gilkinet, in his work cited at the end of section XLIV Mucorini . 



