144 CYSTOPUS, OR WHITE RUST. 



habit. The arrangement of Fungi suggested by Sachs and Cohn 

 is one of the best-known attempts of this nature. They proposed 

 the division of Fungi into four classes, namely — Protophyta, 

 ZYGOSPOREiE^ Oospores, and Carpospore^. 



The first class, Protophyta, contains those simple forms, called 

 Saccharomycetes, or Yeast Fungi, and Sc/iizomyceks, or Bacteria, 

 etc. No sexual organs are found here, and even no non-sexual 

 organs, the multiplication of individuals being effected by the 

 fission or separation of the ordinary vegetative cells. 



The second class, Zygospore/e, contains all those fungi in 

 which sexual reproduction takes place by means of conjugation, 

 the essential characteristics of the process being that the two cells 

 which take part in it are alike, and produce, by the coalescence of 

 their protoplasmic contents, a cell of peculiar form, the Zygo- 

 spore, which usually remains for a time dormant, and is then 

 termed a resting spore. Conjugation is the simplest form of 

 sexual reproduction, but the mere fact of sexuality shows an 

 advance in the mode of reproduction. In keeping with this, the 

 Zygospore.e manifest, generally, a higher degree of organisation 

 than the Protophyta. The principal representatives of this class 

 are the Miicors^ or Moulds, which are, however, also propagated 

 by means of a non-sexual or reproductive cell, or conidium. 



To the next class. Oospore.^, belong those fungi which are 

 reproduced sexually by means of Oogonia and Antheridia. In 

 this class is included Cystopus, and as the details of the sexual 

 reproduction were fully described when speaking of that fungus, it 

 need not be repeated. It will be remembered that here also 

 there is an alternative, non-sexual reproduction by means of 

 conidia. De Bary gives the following summary of the oosporous 

 Fungi : — Pythiiun. — Most of the protoplasm of the antheridium 

 passes into the oosphere. — PJiytophthora. — A small quantity of 

 the antheridial protoplasm enters the oosphere. — Peronospora. — 

 Probably the same process as in the preceding genius. — Sapro- 

 legjiia. — The antheridial tube does not open into the oosphere, 

 and no passage of substance can be observed. — In -S. to?'ulosa 

 and 6". asterophera no antheridial tubes are developed, and in 

 another species no antheridia. 



In the last class, Carpospore^, are included all the true 



