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SUMMARY OF CURRENT RESEARCHES RELATING TO 



direction. Therefore, the author says, there cannot be any real distinction 

 between body-cells and germ-cells. (There remains, however, this 

 •distinction, that a fertilized ovum can develop into an offspring, which 

 no de -differentiated somatic cell or pair of cells can do.) Specialized 

 cells even in Vertebrates show in varying degrees the power of de- 

 differentiation and new specialization. But there is a time in ontogeny 

 when further specialization of cells involves the loss of capacity of any 

 new differentiation ; this is the period at which germ-cells are usually 

 segregated into a distinct tissue. In the higher organisms this may occur 

 early in development ; in Hydrozoa it never occurs. J. A. T. 



Coeloplana. — Taku Komai {Annot. Zool. Japon., 1920, 9, 575-84, 

 5 figs.). Description of a Ccdoplcma bocJci sp. n., found abundantly as a 

 commensal of a littoral species of Dendronephthya, common near Misaki. 

 It differs from C tvilleyi and C. mitsuTcuri from the same locality in 



Larva of Coeloplana bocki, adhering to the substratum by the thin " 

 expanded sole. The main body is laid back and seen on the 

 transverse plane, x 170. 



ph.\ inner part of pharynx ; pg., pigment spots ; ce., oesophagus ; 

 t., tentacle; t.sh., tentacle sheath; s., aboral sense-organ; 

 pp., polar plates ; ph.f., pharyngeal folds 



being much smaller, in peculiarities of coloration, and in having two to 

 five lobe-like processes around the periphery of the polar plates. It is 

 hermaphrodite, and some specimens overlay clusters of developing eggs 

 in direct contact with the ventral surface. The segmentation and gas- 

 trulation are as in other Otenophores, and there is a Cydippid larva. 

 There can be no doubt that the genus is derived from a Cydippid stock 



