318 SUMMARY OF CURRENT RESEARCHES RELATING TO 



confirmed on Gorallium rubrum. Solid particles of carmine are ingested 

 by the endoderm cells of the mesenterial filaments, body-wall, and endo- 

 dermal canals. The endoderm cells of the ventral mesenterial filaments, 

 the body-wall, the canals, and cords in the mesoglcea, are frequently 

 amoeboid. The presence of ingested carmine particles in the cells of 

 the mesoglceal plexus indicates that they have been conveyed from the 

 ccelenteric cavities of the zooids to portions of the colony apart, or even 

 remote, from the zooid. The cells of the so-called " mesoglceal nerve 

 plexus " are amoeboid, and the so-called " nerve-fibres " are their pseudo- 

 podia. The mesoglceal plexus is more intimately connected with the 

 endodermal than with the peripheral ectoderm tissues, and the so-called 

 "nerve-cells and fibres" are immigrant endoderm cells, forming a 

 nutritive as well as a sensitive plexus. Another interesting point is 

 that a reduction of the digestive surface in tropical forms is associated 

 with a corresponding increase in the number of zoochlorellse. 



Monograph on Primnoidse.* — J. Versluys has done a notable piece 

 of work in his memoir on the Primnoids of the Siboga Expedition. He 

 has not only described numerous new and interesting species, but he has 

 put our knowledge of the whole family on a more secure basis. His 

 discussion of the architecture of the polyps is accompanied by a series of 

 exceptionally fine text-figures, and the phylogenetic discussion is also very 

 valuable. There is a suggestive chapter on geographical distribution. 



Sclerites and Canals of Primnoids.f — F. Menneking has studied 

 Stadiyodes ambigua Studer, Galigorgia Jiabellum Ehrb., Galyptrophora 

 agassizii Studer, Amphilaphis abietina Studer, and Thouarella variabilis 

 Studer. In these he finds a canal-system of eight main canals and 

 numerous accessory canals, except in the species of Amphilaphis, which 

 has, apart from accessory canals, only four main canals. All the five 

 species have a more or less strongly marked siphonoglyph on the dorsal 

 surface of the polyp. The end of the partitions between the eight main 

 canals shows a triangular thickening, perhaps a vestige of a mesenteric 

 filament. The partitions are derived from mesenteric folds. All the 

 species had ova in the canals. The analogy between the internal struc- 

 ture of Amphilaphis abietina and that of Pennatulids is commented on. 



Axis of Alcyonarians.J — Th. Studer contrasts the view of von Koch 

 and others that the axis is a simple excretion of the ectoderm, with the 

 view of Lacaze-Duthiers, and Kolliker (to which he has previously 

 expressed his adherence), that the axial skeleton is formed either by the 

 mesoglcea, or by formed elements which penetrate from the ectoderm 

 into the gelatinous mass of the intermediary substance. In Scleraxonia 

 the axis is due to spicules, which have their origin in the mesoglcea ; in 

 Alcyonium palmatum the niesoglsea gives rise to horny substances ; in 

 Eunicella graminea the spicules have an important role in making the 

 axis, forming centres around which the horny substance is deposited. 

 They are subsequently absorbed. From a study of Telesto and Godo- 

 gorgia, Studer has been led to the theory that in other cases (Gorgonacese) 



* Siboga-Expeditie, Monographic xiiia. (Leiden, 1906) pp. 187 (10 pis., 178 figs., 

 1 map.) t Arch. Natur. Ges., lxxi. (1905) pp. 245-66 (2 pis.). 



% Arch. Sci. Phys. Nat., xx. (1905) pp. 581-4. 



