1881. ] Recent Literature. 465 
are by Mr. Kent regarded as forming simply a single order 
(Spongida) of Flagellate Infusoria and standing next to his order of 
Choano-Flagellata, represented by the stalked, collared Codosiga, 
Salpingceca, and Protospongia. 
The structure of the Infusoria proper, are then described with 
much clearness and detail, as well as their reproductive phenomena, 
the author devoting considerable space to the modern view of 
Balbiani and the opposing one of Engelmann and Biitschli as to 
the nature of reproduction in the Infusoria. While not accepting 
Balbiani’s views, afterwards confirmed by Kolliker, Stein,Claparéde 
and Lachmann, that the nucleus is an ovary and the nucleolus is 
other observers and moderate and original in the views presented. 
Mr. Kent believes with Clark that the sponges are colonies of col- 
_ lared flagellate infusoria, and considers that the Protospongia is the 
connecting link between the genuine Flagellata with acollar andthe 
Sponges. He considers that the fact that the collared cells lining 
8 genuine Infusoria, is a powerful argument in favor of their 
lagellate affinities. The strongest argument against the Proto- 
under 
and 
