532 SCIENCE PROGRESS 



the different forms assumed by one fungus, leads to simplifica- 

 tion, and the burden of nomenclature should be lightened for the 

 fungologist of the future, even though new species continue to 

 crop up. 



The ease with which fungi can be cultivated in the laboratory 

 has made them favourite objects for physiological and cytological 

 investigation. Nuclear division takes place by karyokinesis, as 

 in other groups of plants, though the phenomena of division 

 vary considerably for the different forms and stages of develop- 

 ment. In many cases the nuclei are so small that the details 

 cannot be followed. 



The occurrence of sexuality has long been known in the 

 filamentous fungi, both in the oomycetes and the zygomycetes, 

 though in some of the species the sexual organs are now 

 functionless. A. H. Trow has studied AcJilya, and has traced 

 the sexual process in that genus of Saprolegniaceae. Ruhland, 

 a German botanist, has recently described the variations that 

 take place within the genus Albugo, which tend to prove its 

 close relationship to Peronosporese. A. F. Blakeslee reports 

 most interesting work on the Mucorini. The rare and uncertain 

 occurrence of the sexual zygospores in that Order has been 

 explained to be due to this or that unfavourable condition of 

 the substratum, and various recipes have been recommended 

 by fungologists for their successful cultivation. Blakeslee has 

 discovered, and proved beyond a doubt, that plants of most 

 species of the Mucorini are unisexual, and zygospores are only 

 formed when two different strains, termed by him ( + ) and ( — ), 

 are grown together. Zygospores are then formed at the points 

 of contact of the two plants. 



The general question of sexuality in the higher groups was 

 accounted by many as settled when that lifelong investigator 

 Brefeld announced " that no fertilisation process occurred in 

 any group except in the Phycomycetes." Improved methods 

 of fixing, staining, etc., have made it worth while to attack the 

 subject again, and R. A. Harper led the way by his work on a 

 minute ascomycetous fungus, Sphcerotheca castagnei. He found 

 that both antheridium and ascogonium were present, and that 

 fusion undoubtedly took place between the nuclei of these 

 organs. This discovery has stimulated others to work in the 

 same field : some, like M. Dangeard, to a fierce denial of Harper's 

 interpretations ; others to verify and support his findings, or to 



