﻿STARR— AY TON I A 



ss 



else the egg shrinks, so that there is considerable space between 

 the egg and the upper part of the venter. The egg then generally 

 contains large, perfectly spherical globules that stain deeply red 

 with safranin; the shape suggests a fatty food substance. The 

 breaking down of the canal cells leaves the egg invested with a 

 great amount of striated mucilaginous substance which often fills 

 more than half the venter (fig. 28). When the first division of the 

 embryo occurs, all the cells of the venter have divided. Growth 

 continues in the stalk, the venter, and the lower part of the neck 

 until an extraordinary amount of tissue is developed about the 

 embryo and the neck is greatly elongated, curving up above the 

 cushion of the receptacle (fig. 29). 



Sporogonium 



The embryo develops in the usual way, beginning with a trans- 

 verse wall. At first the seta appears as of considerable length 

 when compared to the whole body (fig. 30), but later the capsule 

 and foot develop more rapidly, so that the seta comes to be incon- 

 spicuous (figs. 3 1 and 33) . The foot is well developed as an absorb- 

 ing organ, the cells next to the thallus being large and slightly 

 rhizoidal in shape. Just within the walls of these cells and of the 

 adjoining cells of the thallus there is a granular deposition, probably 

 related to the passage of nutrient material from the thallus to the 

 parasitic sporogonium. The cells of the thallus respond to the 

 mvasion of the foot by dividing, as is shown by the cells nearest 

 the foot being smaller than elsewhere. As the cells break down, 

 a mucilaginous deposit remains, marking the limit between foot 

 and thallus (fig. 32). As the sporogonium matures, the starch 

 contained in the cells of the thallus near the foot disappears, 

 and in all the cells of the receptacle it is scantier than in earlier 

 stages. 



The history of the development of the capsule and of the 

 involucre, resembling the valves of a clam shell, has been 

 described by Leitgeb. It might be added that a few cells at 

 the base of the capsule remain sterile, but there is no regular 

 elaterophore. 



