ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 317 



nective-tissue fibres, but there are none in the interior. When the star- 

 fish is irritated and contracts its skin, small drops ooze out, and it is 

 likely that the secretion has some protective significance. 



Modifications in Development of Sea-Urchins.* — Karl Peter has 

 made experiments with the eggs of Spharechinm granular is, in order to 

 determine " individual variations in development." He finds that the 

 gastrulas, which were reared at a temperature higher than the normal,, 

 develop quickly, and show much greater deviations in the number of 

 primary mesenchyme cells than those reared in cold sea-water. 



Anatomy of Pentacrinus.f— A. Reichensperger gives an account of 

 the antiambulacral nerve system, the " chambered organ " and cirrus 

 vessels, the dorsal or glandular organ, and the gonads in Pentacrinus 

 decorus Wy. Th. The chambered organ is formed of a thin layer of 

 connective-tissue provided with a distinct endothelium. All its parts 

 contain dark granules of doubtful nature. Its five chambers end blindly, 

 it sends branches into the stem, and these are connected with cirrus 

 vessels. 



Ccelentera. 



Medusae from Amboina.J — Otto Maas reports on a collection of 23 

 forms made by Bedot and Pictet. There are no new species, but the 

 collection is of much interest as showing the very wide distribution of 

 pelagic and littoral Medusas. 



Ontogeny and Inteipretation of Siphonophore Colony.§ — R. Wol- 

 tereck gives some notes on Siphonophore development, and endeavours 

 to explain the Siphonophore stock and its parts. The Chondrophorse 

 (Vellella) in their simple plan of structure are remote from the Calyco- 

 phorida? ; they consist only of the two chief zooids (planula-primary- 

 polyp and terminal medusa) and of the products of the proliferation 

 zone (blastostyle, with tertiary medusas). These simplest Siphonophores 

 show in their development a hint of relationship with the Narcomedusa? 

 — viz. two rudimentary balancing tentacles of the primary zooid. The 

 Siphonophore stock may be regarded as an individual in Huxley's sense- 

 (a chain of forms from egg to egg), which is differentiated into a great 

 number of person-zooids and organ-zooids. Certainly the primary 

 zooid (planula), which becomes the primary polyp, forms an aboral 

 stolon, which is separated into terminal organ and circumpolar prolifera- 

 tion zone (stem). The Siphonophore stock may be derived from pelagic 

 bipolar organisms (" Bipolaria " or primitive hydroid larvas), whose aboral 

 pole in the Narcomedusaa of to-day became a proliferating stolon, with a 

 special terminal organ. 



Digestion in Alcyonaria.|| — Edith M. Pratt discusses the structure 

 and food of Alcyonium, Sarcophytum, Lobophytum, and Sclerophytum, 

 and gives the results of her feeding experiments on Alcyonium digitatum,, 



* SB. k. Preuss Akad. wiss. Berlin, xl.-xli. (1905) pp. 884-9 (4 figs.). 



t Bull. Mus. Comp. Zool. Harvard, xlvi. (1905) pp. 169-200 (3 pis.). 



\ Rev. Suisse Zool., xiv. (1906) pp. 80-107. 



§ Zeitschr. wiss. Zool., lxxxii. (1905) pp. 611-37 (21 figs.). 



|| Quart. Jouru. Micr. Sci., xlix. (1905) pp. 327-62 (3 pis.). 



