62 THE EVOLUTION OF CONTINUITY 



word to denoting the serial and lateral continuity of proto- 

 plasts provided with walls — in other words, of " cells " ; for 

 the multinucleate content of the hypha is really two or more 

 parallel successions of protoplasts in lateral continuity, a 

 fact which can be made out by carefully staining a specimen 

 and examining it under a microscope (Fig. 11). 



In moulds of the Mucor type the hyphse are not as a rule 

 divided by septa. As the result of continued growth, and 

 as described on page 60, spores are formed in spore sacs 

 borne at the ends of aerial branches. Each spore when 

 set free can under suitable conditions develop into a new 

 mycelium, which, if it is intermediate in the cycle, will 

 likewise in time produce spores ; but sooner or later mycelia 



Fiq. 11. — Examples of mould coenocyte showing protoplastic 

 series in lateral continuity. Greatly magnified. 



are formed which produce not spores but gametes. In 

 fact, we have discontinuous mycelia taking the place of 

 the independent cells of the Discontinuously Multicellular 

 Individual in the growth-cycle sense. And as the Mucor 

 cycle is composed of mycelial units which are stages on the 

 road to sex, and others which become sexual, there is exhibited 

 a mycelial alternation of generations. 



A fact of great interest is that at times the Mucor mycelium 

 may go into a " torula " condition, developing chains of 

 distinct cells after the manner of Yeast, or as lines of cells 

 in filamentous series. This confirms the polyprotoplastic 

 nature of the coenocyte. The converse of the phenomenon 

 is to be seen in the cases of certain bacillus-Individuals 



