380 SUMMARY or CURRENT RESEARCHES RELATING TO 



the pigmentary and the hepatic functions ; with regard to the latter 

 we have to note that in the Vertebrata, the liver has two functions ; 

 the first and most important is the reception of certain matters from the 

 blood which are deposited in it ; the second is the excretion of these 

 products. The function of these parts may lie in separate organs, 

 and Saint-Loup thinks that the former is, in the Hirudinea, effected 

 by the cells which line the capillaries in contact with the intestine of 

 NepJielis, and by the yellow globules which are found in the paren- 

 chyma of Clepsine. But the elimination is not effected by bile-ducts 

 but by the pigments ; the function of the bile as a fluid accessory to 

 the digestive juices is performed by the secretion of the walls of the 

 digestive tube. 



The study of the development of the liver in certain invertebrates 

 and in the vertebrata has shown that it is formed at the expense of the 

 walls of the intestine, and sometimes from a diverticulum of it ; the 

 author thinks that, in the Hirudinea, it is formed not only by this por- 

 tion of the intestine, but also by yellowish-brown spherules, and it is 

 from this point of view only that we can give to the tunica villosa 

 and homologous organs of worms the definite name of liver. 



Otocysts of Arenicola grubii.* — E. Jourdan describes the otocysts 

 of Arenicola grubii as being placed in the middle of muscular bundles at 

 some distance from the hypoderm, and as surrounded by the connec- 

 tive envelope of these bundles. They are united to the oesophageal 

 commissures by several nerves, and are placed at the side of the dorsal 

 surface. The otocysts are always perfectly circular, and their cavity 

 measures • 14 mm. in diameter, while the sphere itself is • 22 mm. in 

 diameter, so that the walls are of some thickness. These walls are 

 formed by a layer of fusiform cells, a plexus of fibrils, and a connec- 

 tive envelope. Only feeble indications of cilia could, with difficulty, 

 be detected. The cells narrow at their base and curve about in 

 various directions, anastomosing to form a very delicate layer of 

 fibrils which, at the base of the epithelial layer, unite to form a zone 

 intermediate between the nerve-fibres and the base of the cells. The 

 otoliths, like the otocysts, are always spherical, but they vary greatly 

 in size and number. 



Manayunkia speciosa.t — E. Potts supplements Dr. Leidy's de- 

 scription of this genus (erroneously recorded as Manyunkia at p. 231) 

 by former observations of his own, demonstrating its strictly fresh- 

 water habitat, the apparent grouping of the tentacles on two processes 

 on the lophophores, and the difference in the effect produced by the 

 motion of the cilia as compared with a polyzoon. In the latter a 

 powerful " incurrent " bears food to the mouth as a vortex ; in the 

 former, while the motion draws the particles from without or behind 

 the circle towards the tentacles, when they pass by them they are in- 

 fluenced by an " excurrent " bearing them forcibly away. A specimen 

 isolated in a microscopic stage tank, for some reason, left its old 

 tube and formed another, giving him the opportunity of observing 



* Comptes Eendus, xcviii. (1884) pp. 757-8. 

 t Proc. Acad. Nat. Sci. Philad., 1884, pp. 21-4. 



