Circulation of Helix pomatia. 3 



is quite possible to inject parts of the animal in this way, it is 

 done on the supposition that lacunae exist in the body, and that 

 the injection will find its way from them into the vessels. I 

 have therefore tried injections from the aorta, the venous sinus, 

 and pulmonary vein, as well as the foot. 



Before I proceed to give a detailed account of the vascular 

 system, I will give in detail the results obtained from injections 

 both from the tentacle and the aorta, selected from a large num- 

 ber of experiments. 



Animal killed in a jar of cold water; the the foot and ten- 

 tacle extended, but not much swollen with the water. In- 

 jected from the tentacle with warm size and carmine. After 

 cooling, the foot and skin were uniformly red, and no appear- 

 ance of extravasation on their surfaces. On opening the body, 

 the injection was found to have returned to the heart by the 

 pulmonary vein, injecting the anterior part of the pulmonary 

 chamber, but neither the kidney nor that part of the pulmonary 

 chamber situated between it and the rectum. None of the in- 

 jection had found its way into the aorta or its branches. The 

 surface of the crop and the salivary glands were well injected. 

 A large mass of injection moulded between the viscera fell out 

 easily when touched with the end of a scalpel. The venous sinus 

 which runs along the side of the rectum filled well, and also the 

 capillaries on the surface of the oviduct and vas deferens. 



Animal killed in the same way as the last. The parts pre- 

 sented much the same appearance. Injected from the ventricle 

 with size and carmine. On opening the body after cooling, the 

 injection was found to have gone right round the body and re- 

 turned to the pulmonary chamber, richly injecting the space of 

 the pulmonaiy sac between the rectum and kidney (PL I. fig. 2 d). 

 A small quantity of injection was found in the pulmonary vein 

 (fig. 2 b). In this case, and in some other snails injected in the 

 same way, I observed on the surface of the multifid vesicles and 

 in other parts of the body small masses of carmine moulded 

 between the caeca. When detached and placed in warm water, 

 the whole dissolves, without leaving any trace of enveloping 

 membrane : I consider these masses of carmine are merely 

 masses of extravasation from the delicate walls of the capillaries. 

 The capillaries of the digestive tract and generative organ most 

 beautifully injected. The surface of the skin and foot uniformly 

 red. Only a small quantity of extravasation found round the 

 collar, and none observed in other parts of the body. 



I might give numerous other examples, selected from my 

 notes ; but the results are generally the same, and the two ex- 

 amples I have selected give fairly the results of both methods of 

 investigating such delicate structures. Of course it is difficult 



1^ 



