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 !; others were more cautious and professed to be open to conviction. 
On the other hand a misunderstanding of the word pleomorphy Jed men of 
enthusiastic character to extravagant conclusions. ‘The explanation of all enigmatical 
fungal forms has been reserved,’ it was said, ‘for our decade,’ 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 XLV) 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.? 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 chronique scandaleuse will not be further noticed ; this course is justified by 
a critical notice of these matters which appeared some time ago *. 
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, 1864.—Zur Kenntn. einiger d. wichtigsten 
Gattungen d. Coniomyceten u. Cryptomyceten, Halle, 1860. 
2 Bot. Ztg. 1856, p. 799. 
® Bail, Ueber Krankheiten d. Insecten durch Pilze (Ber. d. Vers. d. Naturforscher zu Königs- 
berg) ;—Id. Die wichtigsten Satze d. neuern Mycologie (N. Act. Nat. Curios. 28). 
* 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. Seealso a clear historic 
account by A. Gilkinet, in his work cited at the end of section XLIV (Mucorini), 
