Presidential Address. F. T. Brooks 23 



Lotsy * the Chytridiineae in a primitive group the Archimycetes 

 from which other groups of fungi may be held to have arisen. 



In certain members of the Oomycetes and Zygomvcetes, the 

 atypical development of the hyphae must have struck everyone. 

 With forms Hke Phytophthora in particular, the h^-phae often 

 become vesicular, even under normal conditions, and appear 

 strangely unlike hyphae of the higher fungi. In a new genus 

 {Caeolomotnyces) recently described by Keilint, which has a 

 more marked mycelial development than in other Chvtridiineae 

 although in most respects it appears to belong to this group, 

 the hyphae are particularly wide and irregularly swollen, and 

 show an intermediate condition between a vesicular and a 

 h^'phal mode of development. These aberrant h\-phal forms 

 may be the expression of an ancestry from non-hvphal types, 

 such as protozoal or other protist organisms. 



There are forms also which are classed ^^•ith dithcultv either 

 as bacteria or as fungi, as e.g. species of Actinomyces and 

 Streptothrix, and the possibihty of connection between the 

 higher bacteria and the fungi must not be overlooked, although 

 it is more hkely that the relationship is not of a direct nature. 



The outlook of the \mter upon the fungi is therefore that it 

 is an enormous group of organisms of extreme age and probably 

 of protist origin, which has developed upon independent Hnes, 

 and which shows the same kind of differences between its 

 constituent di\4sions as do other large phvla of plants and 

 animals. Theories of evolution are again in the melting pot, 

 and although the facts of evolution are not in dispute, there 

 seems to be more uncertainty than ever as to the manner in 

 which it has been brought about. By some authorities the 

 fungi are considered to be of polyphyletic origin and some who 

 hold to the protist or Chlorophycean origin of the lower fungi, 

 deny this to the higher fungi, deri\4ng the latter from the 

 Rhodophyceae. However httle is known about the origin of 

 the fungi, we are equally ignorant of their phylogenv. But if 

 a totally different origin for the lower and the higher fungi be 

 postulated there is e\'idently a great gap between the Phvco- 

 mycetes and the Ascomycetes, which is unbridgeable. 5s'ow 

 there are sufficient similarities between the Ascomvcetes and 

 the Phycomycetes to nulhfy the hypothesis that there is no 

 conceivable connection between them. By no great stretch of 

 the imagination a form such as Pyronema ccnfluens may con- 

 ceivably be derived from Albugo Bliti, although I do not \\-ish 

 to imply that this may actually have happened. Although 

 Brefeld's old group of the Hemiascomycetes \\-ill not stand the 



* Lotsy, J. p., Vortrage iiber botanische Stammesgeschichte, Jena (1907). 

 t Keilin, D., On a new t>-pe of fungus: Caeolomcnnyces stegomyiae n. g., 

 n. sp., etc. Parasitology, xiii, p. 225 (1921). 



