124 



MYCOLOGY 



cell mav 



Fig. 38. — Diagrammatic representation of the 

 observed methods of Ascus formation. {After 

 Claussen, Ziir Enlivicklungsgeschicte den Ascomy- 

 ceten, Pyronema conflucns, Zeilschr. fiir Bolanik 

 4 Jahrb., 1912.) 



)enultiniatc, Up and stalk cells 

 and this another, and during 

 this process of proliferation, 

 the nuclei derived by descent 

 from the antheridial nuclei 

 remain distinct from those 

 of the ascogonium (carpogo- 

 nium). Even the two nuclei 

 derived from the tip and 

 stalk cells show this dif- 

 erence, and their descendants 

 remain distinct with the pro- 

 liferation of a new hook with 

 stalk cell. The series of ac- 

 companying figures taken 

 from the paper by P. 

 Claussen will enable the 

 student to understand the 

 process better than a lengthy 

 description. 



The antheridia and 

 oogonia of Sph(Erothe.ca arise 

 as lateral branches of neigh- 

 boring myceUai filaments. 

 The oogonium is cut off from 

 the rest of the hypha by a 

 transverse septa, and pos- 

 sesses a single nucleus. The 

 antheridial branch appears 

 quite near its base and grows 

 upward pressed closely to the 

 side of the oogonium. The 

 antheridial cell with one 

 nucleus is also cut off by a 

 transverse septum. This 

 nucleus now divides and one 

 of the two nuclei passes into 

 the attenuated end of the 



