514 



MOSSES AND FERNS 



CHAP. 



at no time in 5^. Kraussiana are they confined to this apical 

 region, as Miss Lyon states is the case in 6^. apus. 



With the increase in the amount of protoplasm, the very- 

 large central vacuole hecomes reduced in size, and finally, but 

 this does not occur until after the germination of the spore, is 







>> 



Fig. 296. — A, Young macrospore of Selaginella helvetica. The vesicular protoplast, 

 with the primary nucleus, is much smaller than the spore membranes, X400; B-E, 

 S. Kraussiana, sections of the older macrospore, showing the development of the 

 gametophyte; B, X about 200, the others more highly magnified; e, exospore; vi, 

 mesospore; n, nuclei; D, E, show the first cell-formation; D, vertical; E, horizontal 

 section of spore-apex. (A, after Fitting). 



completely obliterated. In microtome sections it appears en- 

 tirely empty, but Heinsen ( i ) states that in tlie living state it 

 is occupied by great quantities of fatty oil. Whether this is 

 the case in 5. Kraussiana was not investigated. 



