Fig. 402. 



Pteris cretica ; prothallus seen from below, bearing an apogamous bud derived not by 

 fertilisation but by direct growth from the cushion. (After De Bary.) 



Fig. 403. 

 Dryopteris pseudo-mas, var. polydactylum. Tissue of prothallus where an apo- 

 gamous growth is to be found, showing on the left a cell with two nuclei, while an 

 adjoining cell has none. At the centre a nucleus is seen passing through a perfora- 

 tion of the wall, and fusing immediately with that of the cell it enters. (After 

 Farmer, Moore, and Miss Digby.) 



