952 SUMMARY OF CURRENT RESEARCHES RELATING TO 



corresponds to that which is eliminated in tho gastric glands of the 

 salamander. Tho gland lias probably a mixed function of secreting 

 both mucus aud ferment. The octopus has no other gastric glands 

 which could furnish digcstivo juices. 



Structure of Pterotrachea.* — Dr. R. Warlomont communicates 

 the results of some studies on Heteropod structure as illustrated by 

 6cveral species of Pterotrachea, 



I. General distribution of integument and musculature. — The body 

 consists essentially of a long tube of very firm gelatinous substance, 

 clothed by a very delicate epidermis, and traversed in the middle by 

 a muscular layer. The two gelatinous layers, internal and external, 

 contain a great number of large round cells with large nuclei. The 

 cavity inclosed by the muscular tubo and by the internal gelatinous 

 layer is traversed by the digestive tube. Beyond the anal extremity 

 the body is prolonged to form the tail. In this the muscular layer 

 is not represented except by four isolated connecting bands. In 

 the gelatinous tissue the round cells are replaced by stellate forms. 

 The fin is a dorsal expansion or diverticulum of the muscular wall, 

 and consists of two muscular plates with longitudinal and oblique 

 fibres. 



II. The nervous system and the ciliated organ. — Dr. Wiirlomont 

 describes the four groups of ganglia: — (1) the three p ir of 

 cerebrals, (2) tho one-paired pharyngeal, (3) the one-paired pedal, 

 (4) the two unpaired visceral ganglia. The distribution of the 

 numerous nerves is then noted. In regard to the interesting nerve- 

 terminations in the skin no new information is communicated. The 

 peculiar ciliated organ consists of two portions, an internal nervous 

 mass continuous with the nerve from the visceral ganglion, aud an 

 external epithelial portion distinctly sej>arable from the former. 

 The nervous band consists of a central fibrous portion and of peri- 

 pheral ganglion cells, and the whole mass is surrounded by a special 

 envelope. The epithelial portion exhibits (1) a thick median mass 

 of large stratified cells, with a deep central depression, marking tho 

 region where the nerve-fibres enter, and (2) a lateral elevation of long 

 ciliated cells. 



III. Visceral region. — The muscular layer of the body ends in a 

 cul-de-sac where the tail is given off. This cul-de-sac is kept in posi- 

 tion by two strands. Behind this and a little further up the muscular 

 bands which run out into the tail are united in a common trunk. Tho 

 cul-de-sac lies above a special muscular pouch — the pericardium — 

 which is quite distinct from the peri-intestinal cavity, and is here very 

 much restricted in its development. The pallial cavity is then de- 

 scribed in detail, as also the branchiae round the ciliated organ, and 

 the general disposition of the visceral sac or " nucleus." As to the 

 digestive tube, the oesophageal portion, which exhibits the usual 

 characters, is enormously extended, occupying the whole length of 

 the body, while the intestine and liver are much reduced. 



* Jourii. de l'Anat. et dc la Physiol., xxii. (18SG) pp. 331-50 (1 pi.)- 



