FUNGI: BASIDIUM FUNGI 331 



isms, regarded as indicating a low type of organization for the 

 plants or animals possessing it, or a low and early stage in the 

 evolution of that organ. The Phycomycetes further possess a 

 mycelium in which there are few or no cross walls dividing it into 

 distinct cells. In extensive portions of the mycelium the proto- 

 plasm is continuous and contains many nuclei.* This peculiar- 

 ity of the mycelium of the Phycomycetes, together with the 

 method of sexual reproduction by antheridia and oogonia, which 

 in such forms as the water molds greatly resembles that of such 

 algae as Vaucheria, has led many to believe that such fungi as the 

 water molds are very closely related to such algae as Vaucheria, 

 and that the water molds may have had their origin from the 

 siphon-algae. This theory is that some of these algae ages ago, 

 became parasitic, or assumed a saprophytic life, as a result of 

 which they lost their chlorophyll. From this point of view there 

 is a two-fold reason for calling the Phycomycetes, the algal fungi. 

 484. The Class Ascomycetes. In this class of fungi the as- 

 cus, a sac-like structure, containing the spores, is the characteris- 

 tic fruiting structure. The number of spores has become, in most 



* The mycelium is ccenocytic, or the p!ant is a ccenocyte, just as the siphon- 

 aceous algee-like Vaucheria are ccenocytes. Coenocyte means a colony of 

 naked cells, or a colony of protoplasts which are not separated from one 

 another by cell walls, each protoplast containing one of the nuclei. Such a 

 plant as Vaucheria, or the mycelium of a colony of a fungus like the bread 

 mold, was formerly believed to represent a single cell, since the definition of 

 a cell at that time predicated a cell wall for its boundary. This theory is still 

 advocated at the present time by some. The argument in favor of this view 

 in the case of such extensive ccenocytic thalli, as is found in the mucors and 

 Vaucheria, that a certain amount of cytoplasm does not remain permanently 

 associated with individual nuclei, that the nuclei move about in the cyto- 

 plasm more or less, does not appear to be very convincing. There is noth- 

 ing really remarkable in this exchange of cytoplasm. In many multicellular 

 plants it is well known that the protoplasts of different cells are connected 

 by strands of protoplasm through minute perforations in the intervening cell 

 wall. In many of the red algae these cytoplasmic communications are often 

 of considerable size and there is probably cytoplasmic interchange between 

 the different protoplasts, so that the nuclei here are not permanently asso- 

 ciated with the same cytoplasm. 



