20 F. W. GAMBLE AND J. H. ASHWOUTH. 



were in a starving condition, a fresh examination is very 

 desirable. A large quantity of albumen is certainly present, 

 which when the specimens are fixed becomes very hard and 

 brittle. 



We have seen small cells (4 ju in diameter) in the blood- 

 vessels of the nephridia, but it is doubtful if these are the 

 blood-corpuscles, which we have not been able to demonstrate.^ 



General Remarks on the Circulatory System. — No 

 other system of organs shows the true segmentation of the 

 body of Arenicola so well as this. The lines of demarca- 

 tion between the somites from one end of the body to the 

 other are marked by the segmental vessels passing from the 

 ventral to the dorsal vessel and breaking up on their way in 

 the body-wall, nephridia, or gills. Throughout the gastric 

 region, however, this arrangement is somewhat disguised, owing 

 to the loss of the connection with the dorsal vessel, an altera- 

 tion caused probably by the necessity for leaving this part of 

 the alimentary canal freely moveable. 



Wiren evidently believes that there is no capillary system 

 except in the gills and the alimentary canal. He suggests 

 that the assimilation of food and oxygen by the tissues is 

 effected chiefly through the mediation of the coelom, which he 

 poiuts out is parcelled off in the intermuscular spaces, by 

 a channelling out of the subepidermic connective tissue, into 

 " perihsemal canals.^^ Though this suggestion is a valuable and 

 correct one, we have found a very perfect system of capillaries 

 in the skin in all parts of the body, and in the nephridia and 

 septa the same is the case. The extension of the coelom into 

 the intermuscular and subdermal spaces has, however, all the 

 appearance of acting as the equivalent of lymph-spaces of 

 higher forms. The transformation of the constituents of the 

 blood into ca3lomic fluid takes place in all probability with 

 especial rapidity in the neighbourhood of the dark chlorogo- 

 genous processes of the ventral vessel (cf. Cuenot, 1891). 



' Since writing tliis we have discovered that these small cells are the 

 blood-corpuscles. 



