Evidence from Protozoans 



379 



points out, skeletal production is no mere matter of simple secre- 

 tion, or still loss of crystallization, but of genuine organic growth, 

 as a detailed study of the completed structure and histogenesis 

 of the parts shows; and by the further fact that the parts con- 

 cerned present characteristic differences for the different species. 

 Thus in the genus Aulosphaera to which belongs the species we 

 have taken as an example, Haeckel recognized twenty-one spe- 



i icnti: i?/i. \rr.\c \\TII A (.\rn:u HOKCERT). 



;is'p., Mstrojn Ic. c.c.-ip., central capsule, n., nucleus. 



cies. Hacker re-examined about a third of these and added four 

 new ones. And the specific distinctions are furnished largely 



in skeletal details. 



(/) Openings in the Central Capsule of the Radiolaria 



Along with these facts of skeletal development may be 

 considered the development of the openings of the central 



