FUNGI: BASIDIUM FUNGI 30! 



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. The mycelium is 

 ccenocylic, or the plant is a ccenocyte* just as the siphonaceous 

 algae-like Vaucheria are ccenocytes. This peculiarity 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, by some of these algae ages ago, becoming parasitic, or 

 becoming adapted to 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. 



469. The Class Ascomycetes. In this class of fungi the ascus, 

 a sac-like structure, containing the spores, is the characteristic 

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



* Coenocyte means a colony of naked cells, or a colony of protoplasts 

 which are not separated from one another by cell walls, each protoplast con- 

 taining 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 coenocytic 

 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 cytoplasm more or less, does not appear 

 to be very convincing. There is nothing really remarkable in this exchange 

 of cytoplasm. In many multicellular plants it is well known that the proto- 

 plasts 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 associated with the same cytoplasm. 



