30 



ZOOLOGY. 



already described. This moner-like being, without a 

 nucleus, is the young Gregarina. 



But soon the Amoeba characters arise. The moner-like 

 young (Fig. 18, D E F] now undergoes a further change. Its 

 outer portion becomes a thick layer of a brilliant, perfectly 

 homogeneous protoplasm, entirely free from granules, which 

 surrounds the central granular contents of the cytode 

 (Haeckel) or non-nucleated cell. This is the Amoeba stage 

 of the young Gregarina, the body, as in the Amoeba, con- 

 sisting of a clear, cortical, and granular 

 medullary or central portion. 



The next step is the appearance of twb 

 arm-like projections (Fig. 18, F), com- 

 parable to the pseudopods of an Amoeba. 

 One of these arms elongates, and, sepa- 

 rating, forms a perfect Gregarina. Soon 

 afterward the other arm elongates, ab- 

 sorbs the moner-like mass, and also be- 

 comes a perfect Gregarina. This elon- 

 gated stage is called a Pseudofilaria (Fig. 

 18, G) ; no nucleus has yet appeared. 

 In the next stage (Fig. 18, H n, nucleus) 

 the body is shorter and broader, and the 

 nucleus appears, while a number of gran- 

 C head nu 2~ ules coll ect at one end, indicating a 

 hinder part^tlwfboir nead> After tnis tlic bod J shortens a 

 c, nucleus. After Gegen- little more (/, J), and then attains the 

 elongated, worm-like form of the adult 

 Gregarina (1C). Van Beneden thus sums up the phases of 

 growth : 



The Moner phase. 



The generating Cytode phase. 



The Pseudofilaria phase. 



The Protoplast (adult Gregarina). 



The encysted Gregarina. 



The sporogony phase (producing zoospores). 



The Gregarinas and Amoeba? constitute Haeckel's group 



