Ill 



AIARCHANTIEyE 



53 



this division. The full-grown archegonium is of more nearly 

 uniform thickness than i-n Riccia, as the venter does not become 

 so much enlarged. The neck canal cells are more numerous, 

 about eight being the common number, but in Targionia the 

 formation of division walls between these is sometimes sup- 



A 





B 



Fig. i6. — Targionia hyjiophyUaiX'.'). A, Longitudinal section of the thallus, X loo ; ar, archegonia ; //, 

 ventral scales ; B, median section through a pore, showing the assimilating cells (cl) below, X300. 



pressed (Fig. 17, C), so that this may account for Janczewski's^ 

 error in stating that the number was always four, as the nuclei 

 in unstained sections might be very easily overlooked. The 

 cover cells are somewhat smaller than in Riccia and do not 

 usually undergo as many divisions, there being seldom more 



^ Janczewski (i), p. 386. 



