ZOOLOGY AND BOTANY, MICROSCOPY, ETC. G33 



layer of circular fibres ; in the centre there is a mass of folded and 

 spiral fibres, and in tbe axis of each tube there is a narrow, irregular 

 canal, lined by cells containing granular protoplasm. By the con- 

 traction of the muscular sheath the animal forces to the exterior the 

 connective elastic mass within each tube ; these become agglutinated 

 with all the bodies with which they come into contact. 



Coelenterata. 



Tissues of Siphonophora.* — C. Chun, in his second paper, f adds 

 some facts as to the nervous system ; he finds that the richly branched 

 ganglionic cells on the upper surface of the disk are connected with 

 one another by their terminal processes, in addition to which tri- 

 angular connecting plates are developed at the points of division. 

 Exceptionally large ganglion-cells lie on the radial muscular fibrils, and 

 give rise to a kind of nerve-ring. Ganglion-cells are also to be found 

 on the inner or chitin-secreting lamella of the ectoderm, but they are 

 not so richly branched or so large ; similar cells have been detected 

 in the ectoderm of the air-sac, and the gastric polypites of Bhizophysa , 

 and in the gastric polypites of Physalia. In these forms the 

 ganglion-cells pass inwards, but in the ectoderm of the tentacle of 

 Apolemia uvaria they remain superficial. As yet the author has failed 

 to find nervous cells in the transversely striated musculature of the 

 nectocalyces of Diphyes, where they might naturally be looked for ; 

 at the same time it was found on experiment that stimulation of one 

 nectocalyx is carried over the whole colony. 



Ciliated and glandular cells are widely developed in the ectoderm ; 

 the tentacular appendages at the base of the fishing-tentacles of 

 Physalia are invested thickly by stinging-cells, among which long 

 supporting and numerous glandular cells are to be made out. The 

 supply of mucus in the Velellidaa may be supposed to take the place 

 of the absent fishing lines. 



The arrangement of the musculature which obtains in the Siphono- 

 phora would appear to be that which is found in most Hydroids ; 

 there arc longitudinal fibres developed from the ectodermal epithelio- 

 muscular cells, and transverse, or circular, endodermal muscular 

 fibrils ; the latter system would appear to be best developed in the 

 air-bladder of Physalia, where in addition to the muscles ganglion- 

 cells may be made out. 



Structures called ciliated funnels are described as being found in 

 the endoderm of the middle third of a tentacle of Apolemia uvaria ; 

 there may be seen three endodermal longitudinal ridges which 

 can be followed almost to the tip of the tentacle ; they consist of 

 non-ciliated mucus-cells, with, on the surface, triangular ciliated cells, 

 containing a coarsely granular protoplasm ; some of these are provided 

 with a ciliated funnel and project freely into the body-cavity. The 

 funnel widens out at its free end, where there are a large number of 

 large cilia which bend over the surface of the cell, and keep up a 

 constant movement. A canal may be made out which extends into 



* Zool. Anzeig., v. (1882) pp. 400-P. 

 t See this Journal, i. (1881) p. 468. 



