122 



PART II. THE INTIMATE STRUCTURE OF PLANTS. 



[ 26. 



(energids), one to each nucleus, and then cell-walls are formed 

 along the lines of demarcation, constituting the units into cells ; 

 when, as is frequently the case, the cytoplasm of the mother- cell 

 is simply a parietal layer, the developing cells secrete a cell-wall 

 over their free surface, as well as the intermediate septa. In 



FIG. 79. Gonidanginm of an Achlya. 

 A Still closed. B Allowing the zoo- 

 gonidia to escape, beneath it a lateral 

 branch c; a the /oogonidia just es- 

 caped; b the abandoned membranes 

 of the zoogonidia which have already 

 swarmed : e swarming zoogonidia. 

 (After Sachs : x 550.) 



Fio. 80. Cell-formation in the asci of Peziza 

 convexula. af Successive steps in the develop- 

 ment of the asci and spores. (After Sachs: 

 x 550.) 



rare cases (e.g. endosperm of Corydalis cava), the cell-walls enclose 

 several energids constituting coeriocytes, but eventually each 

 coanocyte becomes a cell by the fusion of the nuclei (see pp. 90, 118). 



A somewhat similar process of tissue-formation occurs in the Hydrodictyese ; 



