Methods of Preserving Marine Biological Specimens. 525 



dish containing just sufficient sea-water for them to swim freely 

 in. When they are seen to have fully expanded, two drops from 

 a fine pipette containing 1 p.c. solution of hydrochloride of cocaine 

 are added, and the contents of the dish gently stirred with a glass 

 rod. After an interval of five minutes another dose of cocaine 

 solution is added, and this may be repeated a third or fourth time, 

 until there is no contraction of the tentacles on their being gently 

 touched with the fine pipette. Gently stirring, so as to keep 

 the medusae on tlie move, now add from 10-20 c.cm. of 4 p.c. 

 formaldehyde solution, and continue stirring for not less than five 

 minutes. With the pipette, and taking up as little of the cocaine 

 contaminated water as possible, transfer the medusa? to a clean 

 dish containing 4 p.c. formaldehyde ; they may remain in this for a 

 half-an-hour or longer, and should then be stored in the 10 p.c. 

 formaldehyde solution. On no account should the medusee 

 remain longer than is absolutely necessary for their complete 

 narcotization in the water containing the anaesthetic, as the cocaine 

 has a softening action on the jelly. This method may also be 

 successfully used for preserving many of the Hydroid Zoophytes 

 with their tentacles fully expanded. 



Menthol I have found to be a most useful anaesthetic for 

 many marine animals, such as the Hydroid Zoophytes, simple and 

 compound Ascidians, Holothurians, Anemones, etc. The menthol 

 is slow in action, and therefore rarely causes the animal to contract. 

 The specimen is placed in a glass dish with sufficient clear sea- 

 water to cover it to a depth of an inch or more, and crystals of 

 menthol are then strewn upon the surface of the water. The 

 menthol slowly dissolves, and in about twelve to twenty-four 

 hours, according to the size and sensitiveness of the animal, and 

 the amount of water in the dish, the fully expanded specimen will 

 be sufficiently narcotized to be transferred to a suitable killing and 

 preserving fluid. Menthol may be used with some success for 

 obtaining expanded specimens of the Polyzoa, but I am rather 

 inclined to think that better results are obtained with cocaine as 

 the anaesthetic, and then to kill with 10 p.c. formaldehyde solution. 

 Care must be taken, however, to promptly transfer calcareous 

 forms from the formaldehyde solution to 70 p.c. alcohol. 



Specimens in which it is not important to preserve delicate 

 calcareous structure, or are not required for histological work, may 

 be first narcotized and then placed in formol-alcohol, or, if not 

 liable to contract, may be placed at once into this solution, which 

 will kill and preserve them. The formol-alcohol solution is com- 

 posed of 5 p.c. of commercial formol (40 p.c. formaldehyde) and 

 70 p.c. alcohol, and is made up by adding 95 c.cm. of 70 p.c. alcohol. 

 Place the specimen directly into the fluid, which must be changed 

 after twenty -four to thirty-six hours. 



Of the host of fixative mixtures used by various workers, I 



