THE SIMPLER ORGANISMS 113 



cells. The stoneworts, Chara (fig. 48) and Nitclla, show the 

 same phenomena, with eggs and sperms developed within 

 much more highly specialized chambers (ovary and sper- 

 mary respectively) . In the other forms we have been con- 

 sidering any cell might enter into conjugation. But here, 

 the greater part of the cells of the body (bodyplasm) eat 

 and grow and die without descendants, and only the few 

 that are relieved of nutritive functions and wSet apart for 

 reproduction, live on in succeeding generations. 



Among the parasitic protozoans (Order Sporozoa) there 

 are many concurrent modifications of life history and of 

 reproductive methods. One of the most instructive of these 

 is the common gregarine that lives parasitically in the 

 stomach of grasshoppers and crickets, where it is usually 

 found abundantly in summer and autumn. It is a large 

 protozoan when grown, easily recognizable with the un- 

 aided eye, of a yellowish color, and often so abundant that 

 when a grasshopper's stomach is opened it looks as if 

 lined with a layer of yellow corn meal. Each minute grain 

 of the apparent meal represents a single gregarine, or a pair 

 of gregarines in apposition (fig. 68). 



The body of this gregarine shows a constriction across 

 one end which simulates the division between cells; but 

 on closer examination a nucleus is found only in the larger 

 end. The cytoplasm is very densely granular, in so 

 much that the nucleus appears as a clear spot in the 

 midst of it. The ectosarc is thick, and is differentiated 

 into layers, the outermost of which is protective against the 

 digestive fluids with which it is always in contact There 

 are no locomotor appendages — only some contractile 

 fibres developed in the ectosarc, admitting of slow 

 movements of the body. 



These gregarines begin life in the grasshopper's stomach 

 (when swallowed with the food) as exceedingly minute 



