REACTION OF SELACHII TO INJECTIONS 103 



Aquarium in New York. We desire here to express our thanks 

 to the Zoology Department of Yale University, to Dr. Lillie, 

 and to Dr. C. H. Townsend, of the Aquarium. 



MATERIAL AND METHODS 



The animal used in most of the experiments is the dogfish 

 Mustelus canis, which is fairly abundant at Wood's Hole. In 

 the two experiments performed at the New York Aquarium we 

 used Acanthias. In all about seventy-five animals were made 

 use of. These were of both sexes and of various sizes, but most 

 of them were adult males. 



The study was divided into three phases; a) the reaction to 

 non-toxic solutions; b) the reaction to suspended particles, and, 

 c) the reaction to excretory toxins. The solutions used are 

 indigo-carmine, potassium iodide, dextrose, sucrose, pheno- 

 sulphonepthalein, and Weed's potassium ferrocyanide-iron am- 

 monium citrate solution. The supensions are carmine, Congo 

 red, neutral red, and trypan blue. The toxins are potassium 

 chromate, tartaric acid, and uranium nitrate. All were pre- 

 pared with sea-water, which is isotonic with the blood of dogfish. 

 In preparing Weed's solution, sea-water, diluted one-third, was 

 used. 



Injections were made either into the muscles of the tail and 

 back or intra vascularly. In the latter method the large vessels 

 of the pectoral fins were used. A small wooden peg may be 

 used for a hemostat and is very convenient as it can be easily 

 removed for repeated injections. Intravascular injections may 

 be made, also, directly into the sinuses of the head. 



A simple device for holding the animals during the experi- 

 ment may be made from a board 4 inches wide and 2 feet long. 

 A long hole is made near one end for the dorsal fins and a row 

 of nails driven partly in along each side of the board. The ani- 

 mal will be securely held on this if a cord is laced from the nails 

 back and forth across its body. A tube of running water in- 

 serted into the animal's mouth will provide for respiration dur- 

 ing an operation. The entire apparatus with the fish in normal 

 position may be immersed in the aquarium if it is necessary that 



