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. Gonidangium of an Achlya 

 ( x 550). A Still closed. B Allowing 

 the zoogonidia to escape, beneath it a 

 lateral branch c ; a the zoogonidia just 

 escaped ; b the abandoned membranes 

 of the zoogonidia which have already 

 swarmed; e swarming zoogonidia. 

 (After Sachs : x 550.) 



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

 convexula. a /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 coenocytes, but eventually each 

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



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



