Metaphyta Penicillium. 



97 



FIG. 30. Eitrotium re&cns, 

 Bary.) 



at an early date or after a long period of rest. If the condi- 

 tions be favourable, a few weeks are required for the deve- 

 lopment of the asci (fig. 30), in the interior of each cf 

 which by a process of segregation, or free-cell formation, a 

 number of cells are formed. As 

 a general rule, eight cells appear 

 in each ascus, each of which 

 cells is in all essential points 

 extremely like the spore formed 

 from the thallus by ordinary 

 vegetative division. They must 

 not, however, be confounded 

 with them, and the commonly 

 accepted term of 'ascospore' 

 given to these cells is misleading 

 in that respect. Each of these 

 spore-like bodies may, if suitably 

 nourished, develop into a thallus 

 exactly like that formed by the 

 true spore, and in a precisely 

 similar manner. 



It will be necessary for us now 

 to endeavour to obtain some clear 

 conception of the relationship of 

 these different series of pheno- 

 mena to each other, and to trace 

 the homologies between the 

 various stages of the life-history 



Of FllCUS and those Of the life- E, F, two stageslri the d-.velopment 



history of the mould we have just J^. 



been considering. It will con- G ' ascus: H > <asc ' s P re -' 



duce to clearness if we repeat briefly what has been already 



said on these points. 



First, what corresponds in Penicillium to the thallus of 

 Fucusl Obviously what we have named the thallus viz. 

 the felt-like tissue. The thallus of Fucus produced male and 



H 



