ZOOLOGY AND BOTANY. MICROSCOPY, ETC. 67 



are streaminofs of granules in the cytoplasm. The chromatophores can- 

 not change their shape (in the adult at least) ; they have a syncytial 

 character with nuclear divisions even in the adult ; they show a firm 

 membrane. In expansion the chromorhiza^ show a distinct fibrillar 

 structure. 



Blinded Crustaceans lose the power of colour-change. The amount 

 of blue pigment in the chromatophores and in the body tissues is 

 diminished, while the white granules increase. In Cramjon there is 

 pigment-expansion in darkness (natural or artificial). Blinded indi- 

 viduals do not react to artificial darkness, but at night tliey pass from 

 their pathological light hue to almost normal dark coloration, becoming 

 light again*in the morning. 



Development of Winter Eggs of Daphnia.*— Conrad YoUmer has 

 studied the slow development of the so-called " winter ova " of Daphnia. 

 There is total segmentation till thirty-two cells are formed, the yolk 

 being divided into ]?yramidal cells meeting in the centre. Multipolar 

 delamination then ensues, forming central yolk-cells which fill up the 

 interior, and are surrounded by a blastoderm which also contains much 

 yolk. While the blastoderm is aquiring more and more of an epithelial 

 character, a large number of cells migrate to a circumscribed area on the 

 future ventral surface. They form the primordium of the gonad. 

 Shortly before the resting stage is reached, the sensory apical plates 

 arise as paired thickenings at the anterior end of the blastoderm. 

 After the resting period polar emigration on the ventral surface leads 

 to the formation of the " lower layer," the median part of which forms 

 the gut and the side wings the mesoderm. The yolk-cells do not take 

 part in forming the mid-gut. During the establishment of metameres, 

 the gonadial primordium divides into two. The development during 

 the resting period is very slow, but does not stop unless the ^^g be 

 frozen or desiccated. The eggs differ greatly in their individual irrita- 

 bility to external stimuli. 



Adriatic Cladocera.t — L. Schweigger, in reporting on Adriatic 

 Cladocera, calls attention to the fact that they are smaller than their 

 representatives in northern seas, except in the case of Podon intermedins 

 which sometimes attains the size it shows in the north. The same note 

 has been made by Steuer in comparing Boreal and Adriatic Copepods. 



Annulata. 



Pelagic Aphroditidae.l— C. Yiguier describes three pelagic delicate 

 iovms—Folynoe pelagica (Viguier, 1886), Quetieria pelagica (Viguier, 

 1911) and Frennia dubia g. et sp. n. He refers also to Nertnchseta 

 grimaldi (v. Mar. 1892), Drieschia pelagica (W. Mich. 1892), '^"^1 D. 

 pellucida (Moore, 1904), which are likewise pelagic. Perhaps Herdman- 

 ella gracilis (Ehlers, 1908) should be added to the list. 



* Zeitschr. wiss. ZooL, cii. (1912) pp. 646-700 (2 pis. and 12 figs.), 

 t SB. Akad. wiss. Wien., cxxi. (1912) pp. 239-72 (7 figs.). 

 : Ann. Sci. Nat. (Zool.) xv. (1912) pp. 85-99 (2 pis.). 



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