A METHOD OF USING MAGNESIUM SULPHATE FOR THE 

 AN/£STHETlZATION OF MARINE ANIMALS. 



While on a collecting trip in tlie Philippine Islands this spring, I 

 used a method of anajsthetizing marine forms with magnesium sulphate 

 which proved very successful. The method may not be new to many 

 workers, certainly the principle is not. Since I do not know of any 

 zoologist who uses magnesium sulphate in just this way, I venture to 

 publish the method and hope some one else ma}^ find it useful. Success 

 in using magnesium sulphate lies in securing its quick diffusion through 

 the water in sufficient quantity, without causing any mechanical disturb- 

 ance of the animals to be anaesthetized. If a heap of crystals of the salt 

 is placed on the bottom at one side of a dish of water, solution and 

 diffusion are very slow, and attempts to hasten these processes are 

 apt to result in the contraction of sensitive forms. Some workers have 

 made a large quantity of a saturated solution of the salt, which was 

 then led through a tube to the surface of the dish in which were the 

 animals to be stupefied. I believe this method gives good results; but 

 it is a difficult one to use in ordinary field collecting, where room and 

 apparatus are limited. 



The forms on which I have been working this year have been mostly 

 corals, alcyonaria, and gorgonians, with some hydroids and worms. Most 

 of these are quite sensitive. Many of the gorgonians are very slow to 

 expand after they are brought in, and are extremely ready to contract 

 at any time; and I have failed completely in securing well-expanded 

 specimens by the first method mentioned. 



The method which I have used successfully is as follows : 



A considerable quantity of the magnesium sulphate, say 50 to 250 grams, is 

 tied in a piece of cheese cloth and hung over a dish of water so that the bottom 

 of the bag barely dips into the water. It does not seem to matter whether the 

 bag is directly over or to one side of the specimen to he anaesthetized. Streams 

 of the sulphate solution can be seen descending at once through the water in the 

 dish. Even extremely sensitive zooids do not seem to be disturbed by the streams 

 of the salt solution. I have sometimes used two bags of the sulphate when a 

 considerable number of specimens were in one large dish. In order to preserve 

 some of the larger specimens, I have antesthetized them in dishes holding 6 gallons 

 of water. Anaesthesia of some of the alcyonaria can be completed in fifteen 

 minutes, and of most gorgonians in half an hour. 



On this same trip I used successfully A. G. Mayer's method of anass- 

 thetizing meduste by carbon dioxide. The charged water is also helpful 

 in the case of some alcyonarians and gorgonians, although it must be used 

 in conjunction with magnesium sulphate. To other related forms the 

 carbon dioxide is an ij-ritant. 



Lavteence E. Griffin. 



