July 6, 1893 J 



NATURE 



225 



whose brilliant discoveries on the nature of parasitism 

 and the development of the fungi, and above all, the pro- 

 pounding and testing of intelligent theories to explain 

 the facts observed, will never be forgotten. 



Brefeld was driven, at an early period of his investi- 

 gations, to differ entirely from De Bary regarding a fun- 

 damental point in the morphology of the fungi. Certain 

 organs discovered by De Bary in the simpler ascomy- 

 cetes were regarded by him as morphologically sexual 

 organs, and in later years the doctrine of the sexuality of 

 the fungi became a central pivot around which the whole 

 question of the morphology and evolution of these 

 remarkable cryptogams turned. 



As is well known, Ue Bary showed that if his interpreta- 

 tion of the facts was right, we have the principal groups of 

 the fungi ascending along one main path of development. 

 Starting with the Phycomycetes,v;\\\i^ include the mucors 

 and the fungi of the potato-disease and vine-disease (and 

 which are so obviously allied to certain green algfe that 

 it was impossible to doubt that these lower fungi are 

 derived from green algsej, the main path of evolution was 

 traced through the lower ascomycetes, such as the fungi 

 of the hop-disease, and the higher members of the same 

 series — e.g. ergot of rye, the larch-disease, &c., and found 

 to end in the Uredineas or " rusts," andbasidiomycetes — 

 the mushrooms, toadstools, and puff-balls, &c. 



From this main series, branches were regarded as 

 given out at various points, as the Chytridiacea, Ustila- 

 C/V/ft?— the " smuts "and " bunts" of our cereals, &c. — 

 and so on. 



De Bary pointed out very clearly that the most astonish- 

 ing morphological phenomenon observable in the fungi 

 is the gradual loss of first functional sexuality, and then 

 of even the last traces of sexual organs, as we ascend 

 from the lower to the higher fungi. 



Brefeld— and it should be stated that the book before 

 us is almost entirely an admirable short edition of Bre- 

 feld's ten large volumes — maintains that De Bary and 

 his pupils were wrong in interpreting the organs 

 of the ascomycetes in question as sexual, and that the 

 loss of sexuality among fungi occurs much sooner than 

 was supposed. The sexual organs, in fact, disappear 

 within the limits of the Phycomycetes themselves, and 

 He Bary's ascocarp and pollinodium lose all the signifi- 

 cance his hypothesis assigned to them. 



But De Bary's chief mistake — into which he was led 

 by the above interpretation of his own observations — 

 w:is in deriving his ascomycetous series from the wrong 

 '•ranch of the Phycomycetes. Instead of their origin being 

 from the Peronosporea; (Ooinycetes) the ascomycetes are 



rived from the Zygomycetes, their line of descent 



ising through a group containing Proiomyces and 

 I'kelebolus, ind which group Brefeld terms the Hemi- 

 r-ci. 



The oomycetes, indeed, are regarded as leading 



.vhere, except to the richly branched genera which 

 ( nmpose it. 



While the ascomycetes represent an enormously 



branched and successful series of forms which have 



I specialized the type of the sporangium more and more, 



the basidiomycetes (in which the author includes ure- 



; dinea;) have come off from another group of zygomycetes, 



and have specialized the conidium as their type of repro- 



ihictive organ. The half-way group along this line is the 



' stilagineas, and Brefeld terms them Hemibasidii, 



ordmgly. 



The grounds for these revolutionary views cannot of 

 j course be explained in a review. They depend upon the 

 •numerous new facts brought to light by the untiring 

 1 devotion and industry displayed in the iVliinster labora- 

 \ tory, and which are very clearly described and illustrated 

 jin the book before us. 



1 A number of new forms have been discovered, of which 

 the simple Ascoidea rubescens is an interesting example. 



NO. 1236. VOL. 48] 



Very instructive types, as yet unknown in text-books, 

 are Thelebolus, Pilacre, Tomentella, Tylostonta, and 

 some others ; owing partly to the new facts brought out 

 regarding them, and partly to the suggestiveness of the 

 new views as to their morphology, such forms bid fair to 

 become as well known in future hand-books as Mticor, 

 Podosphcera, and Agaricus, are in those of today. 



The generalizations regarding the comparative mor- 

 phology of the reproductive organs of fungi as a whole 

 are distinctly an advance, and show a delightful gleam 

 of light leading to freedom from the chaos of terms the 

 subject has laboured under : "pycnidia" and " spermo- 

 gonia" disappear as such — they are merely chambers in 

 which conidia are developed {conidien-friichte), the ger- 

 mination of numerous spermatia by Brefeld and others 

 having established the conidial character of those mys- 

 terious particles, the spermatia. 



The author's views regarding Chlamydospores will 

 probably cause surprise to many who have not followed 

 the progress of Brefeld's work during the last few years. 

 If these views are accepted, the principal "spores" of 

 Protomyces., the Ustilaginea, and the Uredinece are all to 

 be interpreted as Chlamydospores, homologous with the 

 resting spores of Mucor ; even more startling is the dis- 

 covery of such Chlamydospores (including " oidia" and 

 " gemmje ") among the higher ascomycetes and basidio- 

 mycetes, novelties which are only equalled perhaps by 

 the rich series of true conidial spores found in the latter 

 group. 



Zopf's work on fungi had already prepared us, in 1890, 

 for some of the changes which these discoveries entail, 

 but Zopf was not prepared for anything like the revolution 

 which Von Tavel has accepted — and, indeed, so great a 

 change of front was impossible before the publication of 

 Brefeld's ninth and tenth volumes. 



The new " comparative morphology of the fungi " cer- 

 tainly offers many advantages in the simplification of our 

 views as to the nature of the spore, and promises to 

 remove the bone of contention which this item has always 

 offered to mycologists. We are asked now to accept 

 the following view. There are four types of sporogenous 

 organs in fungi : — (i) The sexual spore, only met with in 

 the lower fungi [Phycomycetes), as the zygospore and the 

 oospore, and gradually losing the sexual character 

 within the group. (2) The endospore, formed asexually 

 in a sporangium, and occurring as zoospores (Perono- 

 sporese, &c.), sporangiospores {Mucor, Thelebolus, &c.), 

 or ascospores (all ascomycetes), the ascus being merely 

 a sporangium of definite shape and size, and containing 

 a definite number of endospores. (3) The conidium, 

 which starts as a one-spored sporangium where the 

 sporangial wall and that of the contained spore fuse, 

 illustrated by the "yeasts" of Ustilagineas and many 

 ascomycetes, the "sporida" of Uredinea;, and the 

 " conidia," " stylospores," " spermatia," &c., of Uredineae 

 and ascomycetes. The " Basidiuin " is merely a special- 

 ised conidiophore where the position and number of the 

 conidia (" basidiospores ") are constant, and true conidia 

 occur in the group in addition — e.g. Heterobasidion, 

 Tomentella, &c. Indeed, it is the play on this type 

 leading to gradual specialisation which characterises 

 the whole Basidiomycetous series. (4) The Chlamydo- 

 spore, which, in the form of the type or of so-called 

 " oidia," " gemmae " occurs generally in all the series, 

 and becomes specialised into " fructifications " in the 

 Uredinea. 



This is perhaps a fair sketch of the central ideas of the 

 new school, though it by no means summarizes or even 

 mentions dozens of other interesting points brought out 

 in the book under review, such as the remarkable evolu- 

 tions of the germination — e.g. in Nectria — of the conidio- 

 phore — e.g. in Peziza — of the conidium, the basidium, 

 the ascus, &c. 



In conclusion, it may be pointed out that although Von 



