90 Proceedings of the Royal Fhysical Society. 



M. Perrier has recently published two admirable and exhaus- 

 tive memoirs/ inasmuch as there is no necessity for an 

 injection to demonstrate its presence. If this were actually 

 necessary, the difficulty of successfully injecting such small 

 animals would naturally introduce abundant source of error, 

 but as a matter of fact it is not in the least necessary, for if 

 the animal be killed by immersion in spirit, the capillaries 

 remain injected with their own blood, and are extremely 

 conspicuous under the microscope as yellow-coloured branch- 

 ing tubes. In Urocliceta Perrier does not figure or describe 

 intra-epithelial capillaries, and in Poiitodrilus he expressly 

 states that the terminal ramifications of the vascular system 

 are contained in the circular muscle-layer, beyond which 

 they do not penetrate. 



Although the first description of intra-epithelial capillaries in 

 earthworms is contained in my own paper already quoted, the 

 fact itself was not new, since Professor Lankester had pre- 

 viously pointed out that the epidermis of the leech is vascular; 

 in this Annelid, moreover, the capillaries are accompanied 

 by pigmentiferous connective tissue cells.^ The epidermis of 

 Perionyx agrees with that of the leech, and differs from that 

 of all other earthworms in being pigmented, but the state of 

 preservation of the specimen from which my sections were 

 taken was not sufficiently good to enable me to decide 

 whether the pigment was intrusive or simply contained 

 within the epidermic cells themselves. 



In Lumhricus the epidermis is separated from the subjacent 

 layer by a thin elastic membrane, from which are given off a 

 number of fine processes, which ramify between the individual 

 fibres of the transverse muscular coat. In both Perionyx and 

 PericJmta this elastic network is very highly developed, and 

 the meshes of which it is composed are in most cases five or 

 six times the diameter of the enclosed muscle fibrils, which 

 are thus furnished with a very strong elastic sheath, com- 

 parable perhaps to the elastic sareolemma of the vertebrate 

 muscular fibre. The longitudinal muscles are similarly sur- 



1 Arch, de Zool. Exper. , t. iii. and t. ix. 



'^ Mr A. G. Bourne has recently (Proc. Eoy. Soc, 1883, No, 229) proved the 

 presence of an epidermic plexus in ail the Gnathobdellido?. 



