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Mr. J. S. Dunkerly, B.Sc, gave " AEesume of our Knowledge 

 of the Choanoflagellata." He said that these organisms, owing 

 to their minute size, are a little-known group of the Protozoa. 

 Early microscopists described forms possessing three processes, 

 probably identical with collar boundaries and flagellum. J. Clark, 

 in America, was the first to describe the true structure of these 

 forms, and Saville Kent described most of those at present known, 

 later workers being Biitschli, Entz and France. Fisch has 

 described the process of reproduction by division. 



A typical Choanoflagellate has an oval, naked protoplasmic 

 body with nucleus, contractile vacuole, one flagellum, and 

 surrounding the base of the flagellum, a protoplasmic mem- 

 brane the collar, which is usually basin-shaped. Food 

 particles are brought into the region of the collar by the 

 movement of the flagellum. Saville Kent described such food 

 particles as passing down inside the collar to be absorbed by 

 the body-protoplasm, but later workers are of opinion that the 

 current passes down outside the collar. Food vacuoles may be 

 seen at the base of the collar. The flagellum arises from a 

 staining granule, the blepharoplast, which, apparently, was not 

 seen by Saville Kent and other early workers. In division, the 

 flagellum is retracted ; the collar sometimes divides, if not also 

 retracted. Cysts have been observed to give rise to flagellate 

 individuals, which swim freely and gradually acquire a collar. 



The simplest naked form is Monosiga ; a similar form, but on 

 a branching stalk, is Codonosiga. The genus most rich in species 

 is Scdpingoeca, a form living in a lorica, or case, secreted from its 

 body. There are various beautiful forms of this " house." A 

 similar form, in which, however, the individuals have their 

 houses connected with each other by stalks, is Folyoeca, a rare 

 form observed by Saville Kent in aquarium tanks at Hastings. 

 The lecturer had also noticed it occurring in tanks at Plymouth 

 Biological Laboratory. Proterosjpongia is an interesting form 

 with a gelatinous body, in which are embedded collared cells and 

 amoeboid cells. Saville Kent considered the sponges to be 

 derived from a similar form, but our present knowledge of 

 sponge development renders this very unlikely. Some double- 

 collared forms which have been described resemble loricate 

 forms, in which the neck of the lorica may have been mistaken 

 for a second collar. 



