9 6 



THE PROTOZOA 



formed by the same animal. The history of the buds is different in 

 different individuals. In the simplest cases, the bud merely drops 

 off the parent and remains on the bottom for some days in an 

 amoeboid state. In other cases, flagella are formed, and the buds 

 move about like swarm-spores, although after a couple of days these, 

 too, become amoeboid. A few days later silicious spicules appear 

 in the vicinity of the nucleus, and soon after make their way to the 

 periphery, where the shell is formed (Fig. 53). Clathrulina also 

 forms buds in a similar manner, and has been observed by Cienkow- 

 sky, Greeff, Hertwig, and Lesser; the observations thus are as well 



B 





D- E F 



Fig- 53- Nuclear division and spore-formation in Heliozoa. [SCHAUDINN.] 

 A. A vegetative cell of Spkcerastrum, with the axial filaments focussed in a central granule 

 (division-centre or " centrosome"). B-D. Division of the nucleus in Acanthocystis. E. F. Flag- 

 ellated and amoeboid swarm-spores formed by budding. G. Exit of the central granule from the 

 nucleus. 



established as in Acanthocystis. The number of buds is not so large 

 as in the latter form, and the process is not unlike simple division. 

 The body divides into three dissimilar pieces, two smaller and one 

 larger. The latter remains within the old shell, but the former 

 develop flagella and swim about like swarm-spores. In about half 

 an hour they lose their flagella, settle to the bottom, throw out pseu- 

 dopodia, and develop a stalk. 



Conjugation has only rarely been seen among the different kinds of 

 Sarcodina, and further observations must be made before it can be 

 considered a widespread phenomenon. A few authentic observa- 

 tions, however, show that it occurs in some cases. Biitschli ('74) 



