A METHOD OF PRESERVING LAEGE NUDIBEANCHS. 



W. J. CROZIER. 



Contributions from the Bermuda Biological Station for Research, No. 65. 



Those who have had occasion to study collections of nudi- 

 branchs, especially when they include specimens of the larger 

 tropical species, have doubtless often wished that the organisms 

 submitted for their examination had been so preserved as to 

 exhibit in more natural fashion the appearance of these crea- 

 tures when alive. After various attempts to secure good prepa- 

 rations, I find that the simple procedure herein outlined gives 

 tolerably fair results. The method has been tried almost ex- 

 clusively upon Chromodoris zebra, but it seems likely that 

 other large forms will yield equally good preservations when 

 treated in the same way. 



A saturated solution of cocaine hydrochloride is made up in 

 sea water, and 2-3 cc. of this solution is then injected into the 

 heart (or into the region of the heart) of Chromodoris by means 

 of a syringe and hollow needle. A "Record " syringe, such as 

 is used by surgeons, is useful for this purpose. Within an hour 

 or so depending on the temperature, on the size of the animal, 

 and on the exact amount of the narcotic that has been injected 

 the nuclibranch will be fully anaesthetized, usually with the 

 gills and rhinophores fully extended; frequently also the genital 

 papilla will be protruded, and the pharynx everted. It is ad- 

 vantageous to add a few crystals of chloretone to a small vol- 

 ume of sea water containing the nudibranch; furthermore, 

 several injections of the cocaine may sometimes yield a better 

 result than a single dose. 



When completely anaesthetized, the animal may be killed 

 and fixed in 75 per cent, alcohol. Precipitated siirne, on the 

 surface of the body, can be subsequently removed with a camel's 



