hair brush. In order to avoid the distortion which inevitably 

 results if these large nudibranchs are fixed while they rest upon 

 the bottom of a dish, it is well to suspend them vertically in 

 the fixing fluid until they are killed and begin to harden. This 

 may be done by gripping the caudal extremity of the foot be- 

 tween the jaws of a light "artery clamp" or some similar in- 

 strument; or a thread may be sewn through the foot for this 

 purpose. 



The injection of a relatively small amount of a narcotic 

 usually gives much better results than does the attempt to anaes- 

 thetize these nudibranchs by adding magnesium sulphate, or 

 chloretone, to the seawater containing them. In the latter 

 method, not only does the surface frequently become covered 

 with a number of vesicular blebs, edematous in appearance, but 

 also the proper time for removal to the killing fluid must be 

 selected with considerable care. A similar procedure, involving 

 the injection of chloretone into the bodj^-cavity, has been em- 

 ployed by Pearse 1 with holothurians. 



The proper penetration of the fixative is of course important 

 for the conservation of the internal organs. This result may 

 be assured if a fair volume of the fixative is employed, and if 

 in addition an incision several centimeters long is made along 

 the edge of the mantle (preferably on the left side) previous 

 to immersion in the fixative. 



Frequently it is desirable that the normal integumentary 

 colors of the nudibranch should be preserved as faithfully as 

 possible. Two fluids which I have found useful with Ohromo- 

 doris zebra are Merkel's fluid and the sublimate-acetic mixture 

 (saturated aqueous solution of sublimate plus 5 per cent glacial 

 acetic acid). The sublimate mixture in particular gives a very 

 fair preservation of the blue pigment of Chromodoris, which is 

 permanent for six months at least, if not for a longer period. 

 The sublimate precipitates the blue substance so that it is no 

 longer soluble in aqueous alcohol, and at the same time renders 



hearse, A. S. , 1910. Eine Methode, urn Holotburien in ausgedehntem 

 Zustande zu konservieren. Zeits. f. biol. Tech. u. Method., Bd. 2, p. 94-95. 



