INVEETEBBATA, CRYPTOGAMIA, MICROSCOPY, ETC. 459 



creature undergoes no change ; if wo cut off part of a tentacle the rest 

 of that tentacle contracts, but the neighbouring ones give no indica- 

 tions of being affected. 



These considerations are brought into accord with other results, 

 which at first sight would appear to contradict it, by supposing that 

 two systems of fibres, which are connected with one another by 

 nuraerous transverse branches, can be made out in Ceriaiithus ; one is 

 mesodermal and is embedded in the connective substance of that layer, 

 and the other is ectodermal, is embedded in the interbasal network, 

 and gives off, as already said, fibres to the ectodermal and to the meso- 

 dermal cells. 



In the substance of the mesoderm there are to be observed canali- 

 cular spaces, which, as the author thinks, are correlated with the mode 

 of absorption of nutriment in the Actiniae. The amoeboid cells which 

 are found in this layer are looked upon as migratory cells, and they 

 are stated to be much more numerous during the breeding periods. 



Testis and Ovary in Campanularia angulata (Hincks).*— The 

 histological study of the three layers, ectoderm, intermediate lamella, 

 and endoderm, of the body in Hydroids, has led M. J. Fraipont to 

 some new and important facts, of which he gives a summary. 



The small nematocysts of the ectoderm of the tentacles are sur- 

 rounded by a slight protoplasmic layer, often nucleolated and indivi- 

 dualized, to which a palpocil corresponds. This relation is important 

 from the physiological point of view, and that of the mode of action 

 .)f the urticant organs. 



The endoderm of the stolons in the vicinity of the pedicles of 

 female gonangia (Cavqyanidaria angulata), and especially in the 

 branches (C flexuosa), contains larger cells, having, on the one hand, 

 the characters of egg-cells, and passing, on the other, into the endo- 

 dermic cells. 



The free extremity of the appendicular organ terminated in a 

 hook is characterized by the development of the ectoderm, by the 

 accumulation in that tissue of corpiiscles of special structure, and by 

 the considerable attenuation of the perisarc. These data may perhaps 

 serve to settle the natm-c of this organ. 



In the body and tentacles the intermediate lamella, which else- 

 where is amoriihous, presents fasciculated fibrils, which insert them- 

 selves at definite points, and which the author believes to be 

 muscular. 



A gonangium is formed by a gonotheca, a central system of canals, 

 and some gonophores. The axial canal, or blastostylc, spreads out into a 

 hammer-head at the upper extremity of the gonangium, and furnishes 

 laterally those casca at the level of which the gonophores are formed. 

 In C angulata and C. flexuosa the latter do not become either medusa) 

 or semi-mcdus{c, as in other Cani}>anularia: ; they remain in the con- 

 dition of diverticula of the wall of the body, and certain of their 

 cellular elements become ovary or testis. 



* 'Comptcs RcnduH." xr. (1880) p. 4:^; sec 'Ann. nml Mii;:. Nat. IIi>t.,' v. 

 (1880) p. 2G.'). 



2 IT '1 



