262 NpW YORK STATE MUSEUM 



the outline of the animal. The motions are vibratile rotary, with 

 a lateral progression, or whirling in circles like the insect G y r i- 

 nus. Cryptoicus from its position might be mistaken for 

 the spermatozoa of the animal, but may be readily distinguished; 

 the spermatozoa of Helices having either a uniform sigmoid 

 or a spiral body, with an enormous proportionate length of tail, 

 and a slow vibratile motion. 



Plate 13, figure 6, represents some of the varied forms of the 

 animal highly magnified. 



Circulatory system 



Method of injecting the blood vessels. I have found the follow- 

 ing method to be the best in obtaining a complete injection of the 

 circulatory system, and by it I have obtained the most beautiful 

 results, plainly showing all the minute ramifications of the arter- 

 ies and veins. 



The necessary materials are an ordinary hypodermic syringe, 

 with as fine a needle as it is possible to obtain, the finer the bet- 

 ter; as an injection which would not pass through the finest 

 hypodermic needle certainly would not pass through the fine ar- 

 teries and veins. The distal extremity of this needle should be 

 blunt or slightly bulbous. A curved sewing-needle and very fine 

 thread are also necessary. As an injection fluid I have used and 

 found perfectly satisfactory Dr Seller's carmine gelatin. This is 

 sold by the ounce and comes in a solid mass. 



A day or two before making the injection, some of the gelatin 

 should be placed in cold water in a wide-mouthed bottle. The 

 water will soften the gelatin. When it is proposed to use the 

 injection, the bottle can be set in a pan of hot water. Within 

 a short time the gelatin will be completely dissolved. It should 

 be thin enough when hot to enter easily the arteries and veins, 

 but of sufflicient consistency to harden when cold. No rule can 

 be given as to the exact proportion of water and gelatin. The 

 right degree of fluidity must be determined by each student. Use 

 only filtered water with the gelatin, as a small particle of dirt in 

 the water might prevent a successful result. 



Take the animal as soon after death as possible; wash away 

 the mucus. Then, as previously described, remove the shell, 



