340 



THE PROTOZOA 



Pfeffer asserts that the young intracellular stages of the mealworm- 

 gregarine multiply by fission. Porospora, with its remarkable 

 schizogony, is apparently a septate cephaline gregarine of the 



Fia. 151. Diagram of the life-cycle of Ophryocystis, after Le"ger (617, i.). A, The 

 spore setting free sporozoites ; B, the sporozoite attached by its rostrum to 

 the epithelium of the Malpighian tubule ; 0, multiplication of the nucleus 

 of the sporozoite, and growth to form D, the multinucleate or- " mycetoid ' 

 schizont ; E, division of the multinucleate schizont into a number of mero- 

 zoites (F), each of which may become a multinucleate schizont again, or 

 (G, H) may become a paucinucleate or " gregarinoid " schizont ; H, division 

 of the paucinucleate schizont to form young sporonts (/, J) ; K, association 

 of two sporonts ; L, formation of a common cyst round the associated sporonts, 

 and division of their nuclei ; M , formation of three nuclei in each sporont ; 

 N, separation of a gamete (g.) within the body of each sporont, while the 

 rest of the body, with two nuclei, becomes an envelope-cell ; 0, the two gametes 

 have fused to form the zygote (2.) or sporo blast ; P, the sporo blast has as- 

 sumed the form of the spore, and its nuclei have divided into four ; ultimately 

 eight nuclei and as many sporozoites are formed. 



ordinary type. A character such as the possession of the power 

 of multiplication by schizogony is clearly one of great adaptive 

 importance in the life-history of a parasitic organism, and therefore 



