798 SUMMARY OF CURRENT RESEARCHES RELATING TO 



by longitudinal muscles. The mouth leads directly into a cavity, 

 whence arise the gastro- vascular canals, or better, enteric branches; 

 these are very numerous, and do not appear to be definitely arranged ; 

 they anastomose at their periphery. The inner gastric wall dcvclopcs 

 various internal processes; the epithelium is covered by a number of 

 long cilia, and contains unicellular glands. Tho new form differs 

 from Cceloplana in having one instead of two vertical canals; this, 

 which lies centrally below the otolith-vesicle, appears to correspond 

 to a funnel of the Ctcnophora, which is here considerably reduced, 

 and is not an independent structure, but an integral part of the gastric 

 cavity. Dorsally there arc right and left, two small openings which 

 lead directly into infundibular enlargements, from which fine canals 

 pass at right angles to the primary axis. They do not appear to be 

 ciliated. From the primary axis branches are given off in all direc- 

 tions and traverse the parenchyma. The relation of these to tho 

 formation of the longitudinal musculature is very remarkable ; tho 

 canal leads into an enlargement in which are inclosed longitudinal 

 muscles ; those appear to be comparable to tho water-vascular system 

 of Planarians. They are quite primitive in structure, and cannot be 

 regarded as an independent system, but as a body-cavity which com- 

 municates with the outer world by a pair (or possibly more) of 

 orifices. The musculature is closely connected with the layer which 

 forms the surface of the body ; of this there is, first, a well defined 

 body-epithelium, which consists of cylindrical cells ; dorsally there 

 are large gland-cells, the contents of which are clear and transparent. 

 At the base of the epithelium there are a large number of interstitial 

 cells, and there is a basal membrane, which appears to be quite 

 homogeneous and elastic, and has no indications of any cellular 

 elements ; this membrane varies in thickness in different parts of the 

 body. 



The muscles belong either to the dermal system, in which we find 

 all the superficial layers, to that of the dorso-vcntral fibres, or to tho 

 special supply of the ctenophoral plates and tentacles. Among them 

 we find a special system of longitudinal fibres which cannot be 

 homologized with any found either in Ctenophores or Planarians ; 

 it is that which supplies the stellate dorsal structure. Each longi- 

 tudinal muscle represents a single bundle, the middle is occupied by 

 strong fibres, and at the periphery there are thin corresponding cell- 

 nuclei, which surround the bundle on all sides. 



The author regrets that he was unable to make a complete study 

 of the nervous system ; with regard to the otolith-vesicle, he tells us 

 that the pit is bounded by a ridge-like thickening ; the base is some- 

 what complicated in structure ; exactly at its centre there is a clear 

 spongy mass formed of connective tissue, and containing but few 

 nuclei. On either side there is a group of special gland-cells, the 

 nuclei of which are all collected at the base. More peripherally there 

 are two aggregations of elongated, almost filamentar elements, which 

 arc so arranged as to have a conical form. Still more peripherally 

 there is a structure which is formed of rows of cells. These carry 

 stiff hairs which form a support for the vesicle. At the edges of the 



