90 



THE PROTOZOA 



of this peculiar structure remains for the present problematical. 

 In the spores of Derbesia, Davis (" Annals of Botany," xxii., 

 pp. 1-20, plates i. and ii.) has described a condition very similar 

 to that of Lophomonas namely, a double ring of blepharoplasts, 

 which, however, fuse together to form a ring of homogeneous 

 appearance. The blepharoplast-graina are given off from the 

 nucleus. 



Centrosomic bodies may be related, not only to flagella, but also 

 to pseudopodia, especially in those cases in which the pseudopodia 



FiG. 46. Actinophrys sol, showing the axial filaments of the pseudopodia centred 

 on the nucleus. N, Nucleus; pa., pseudopodia; ox., axial filament; c.v., 

 contractile vacuole ; /.., food-vacuole. After Grenacher. 



have become specialized in form and movement, as in the Heliozoa. 

 In this group the relationship of the nuclear apparatus to the 

 pseudopodia exhibits two types of arrangement, which are analo- 

 gous to the two arrangements described above in Mastigina and 

 Mastigdla respectively, and which may be explained by supposing 

 that in the one case the kinetic centre lies within, in the other case 

 without, the nucleus itself. Thus, in Actinophrys (Fig. 46) the 

 numerous pseudopodia are all centred on the single nucleus, in 

 which the centrosome is contained. A variation of this type is 

 described by Schaudinn (43), in the peculiar multinucleate form 



