The anatomy of Lucapina crenulata. 451 



be thrown out during contraction. An injection bulb filled with the 

 fluid was then attached to the rubber tube, and the whole circulatory 

 system filled. The animal is hardened in a few seconds by this method, 

 and every organ is found to be in perfect condition. Van Gehuchten's 

 formula is as follows: 



absolute alcohol 60 parts, 

 chloroform 30 parts, 



glacial acetic acid 10 parts. 



The alcohol used in this mixture was the ordinary commercial 

 quality, about 95%, and I believe the results were practically the 

 same as those where the absolute was used. 



Molluscs injected with Van Gehuchten's fluid are excellent for 

 dissecting out the larger nerves. The muscular tissues are whitened, 

 while the nerve fibers are apparently unchanged, having the yellowish 

 tint characteristic of the fresh specimen. The histological structure 

 of the ganglia come out well with this method of fixing, the cells 

 being in perfect condition. Soon after the animals were injected, they 

 were placed in 70 ''/o alcohol for several hours, then transferred to 

 85°/o, where they were left until ready to use. 



For the dissection of the finer nerve branches, the specimens 

 were injected with a 5 to 10 7o solution of nitric acid, the method 

 of injection being similar to that for Van Gehuchten's fluid given 

 above. They were then put into acid of the same strength for an 

 hour or more, when the shell removed with comparative ease, leaving 

 the surrounding muscles unbroken. A small amount of fresh acid was 

 added to compensate for that neutralized by the shell. The animals 

 are best kept in glass jars while macerating, as light seems to be an 

 important agent in turning the muscles yellow. My best results were 

 obtained by putting the specimens in strong light, where they were 

 allowed to remain for a month or more, that is until the tough muscles 

 of the mantle and foot could be dissected with the tweezers. I find 

 that a low per cent acid gives much better results than a higher one. 

 Of course the maceration is slower but the nerve fibers come out in 

 a much firmer condition. Under this method of treatment the muscular 

 tissues are yellow, while the nerves are lighter colored. 



For nerve dissecting I have found a little device, which I fitted 

 up in the laboratory, of the greatest assistance. By means of a small 

 rubber tube of considerable length a glass tube is connected with the 

 hydrant. The end of the nozzle is drawn out into a capillary tube 

 with a bevelled point, whose sharpened extremity is used like a dis- 



