IQOS] 



YAMANOUCHI—APOGAMV IN NEPHRODIUM 



299 



developed. The central cell, when it remains undivided, grows to a 

 considerable size, with a corresponding increase in the size of its 

 nucleus, which finally assumes a form similar to that of an egg, but 

 it always appears collapsed. When canal ctll^ and egg arc formed, 

 they also appear collapsed. The collapsed appearance of the cen- 

 tral, canal, and egg cells is hkely induced by the artificial treatment 

 of the prothaUia rather than by fixing reagents. 



Whether the egg in 

 such a collapsed con- 

 dition is still capable 

 of fertilization, is ques- 

 tionable, but the writer 

 is inchned to believe 

 that it is incapable of 

 functioning. No case 

 of a sperm having 



pacT 



was 



entered an 



found. 



Not only is the 

 formation of arche- 



gonia extremely rare, showing two different stages in the development of 



but when formed they 

 are very much belated. 

 In all cases in which 



Fig. I. 



pogamous 



shad 



outgrowths ; a 



•onium 



with central cell; ft, 



archegonium with canal cells and egg. 



their formation was observed, apogamous sporophytic outgrowths were 



ifig^ 



Hence 



it is reasonable to suppose that in the apogamous prothaUia a tend- 

 ency to develop sporophytic outgrowths becomes predominant when 

 the power of forming archegonia becomes weak. 



SPOROPHYTIC OUTGROWTHS 



As described before, during the early development of prothaUia, 

 mitoses occur in the vegetative cells Just as in normal prothaUia, 

 except that the mitotic figures are comparatively large. The mitoses 

 continue in the vegetative ceUs and there are organized prothaUia of 

 a single ceU layer in thickness. The general outline of the prothaUia 

 does not show any pecuHarities which might be regarded as charac- 

 teristic of apogamous prothaUia as distinct from normal ones. 



