THE SARCODINA 



247 



In the " schizogony " of the stout forms the nucleus breaks up into a number 

 of daughter-nuclei, as in gemmation ; each daughter-nucleus grows, its karyo- 

 some multiplies by fission, and it breaks up in its turn into granddaughter- 

 nuclei. Continued multiplication of the nuclei in this manner proceeds 

 until the body is filled with vesicular nuclei ; it then breaks up into as many 

 amo3bulae, which are set free, leaving a residual body with the central grain, 

 which degenerates. 



F(O. 102. Wagnerella borealia, showing budding and fission. A, Specimen with 

 a single bud (b) : e.g., central grain ; B, specimen with four buds (b) ; C, en- 

 larged view of the head of a speoimen containing two buds (6) in process of 

 extrusion ; D, speoimen in which the head has multiplied by fission to produce 

 a Phaphidiaphrys-like colony ; six individuals are seen, five of them each 

 with nucleus and central grain, the sixth in process of fission, with two nuclei 

 and two central grains. After Zuelzer (86). 



The Heliozoa are classified into four suborders : 

 SUBORDER I. : APHROTHORACA. Body naked in the active state ; 

 envelopes, sometimes with siliceous spicules, only formed during 



