30 



■es*'- 



ZOOLOGY. 



already described. This moner-like being, without a 

 nuclens, is the young Gregarina. 



But soon the Amoeba characters arise. The moner-like 

 young (Fig. 18, D E P) 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 two 

 arm-like projections (Fig. 18, P), 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'liimentary^canai of" thc body is sliortcr and broader, and the 

 S'°' if^yrrger' rtat; nuclcus appears, while a number of gran- 

 Hou (ao'rf''the\°ead""l' "^^s Collect at one end, indicating a 

 hSv p'art ofSo'bo'dy; ^^•^^d. After this the body shortens a 

 c nucieuB.-Aj-tcr Gegen- little morc (/. J), and then attains the 

 elongated, worm-like form of the adult 

 Gregarina {K). Van Beneden thus sums up the phases of 

 growth : 



1. The Moner phase. 



2. The generating Cytode phase. 



3. The Pseudofilaria phase. 



4. The Protoplast (adult Gregarina). 



5. The encysted Gregarina. 



6. The sporogony phase (producing zoospores). 



The GregarinsB and Amoebas constitute Haeckel's group 



