CHEMICAL AGENTS ON CHROMATOPHORES 183 



in protozoans. Also, that it stopped the movements of the 

 leucocytes. Santesson ('93) found that quinine depressed the 

 rhythm of an isolated frog's heart. Hedborn ('99) observed 

 that quinine depressed an isolated mammalian heart (cat). 

 0. and R. Hertwig ('87) observed that sperm treated with qui- 

 nine had their movement paralyzed. Eggs when treated with 

 quinine after the sperm entered, the conjugation of the pro- 

 nuclei was delayed. Carlson ('06) has found that quinine did 

 not stimulate the ganglion or the muscle of the Limulus heart. 

 It is obvious from the experiments that quinine exhibits no 

 primary stimulating action on the pigment cells of trout em- 

 bryos. Any accurate interpretation of the depressing action of 

 quinine is not possible, since the drug acts in the same way on 

 the nervous tissues and the pigment cells as well. 



SUMMARY 



1. The experiments were performed on the melanophores 

 (pigment cells) of the brook trout embryos, Salvelinus fontinalis 

 Mitchill. Such young trout have only one kind of pigment 

 cells, the melanophores. The young two-day or two- week old 

 trout do not yet react to back ground. The first sign of reac- 

 tion to back ground appears only after the yolk is absorbed. 



2. In the presence of oxj^gen the pigment cells remain ex- 

 panded and the fish live indefinitely. When hydrogen (oxygen 

 want) is substituted for the oxygen the pigment cells contract 

 and the embryos die. Oxygen is necessary for the maintenance 

 of the expansion of the melanophores and life of the trout 

 embryos. 



3. Carbon dioxide excess caused a contraction of the melano- 

 phores. If oxygen was bubbled with the carbon dioxide, the 

 presence of the oxygen had an antagonistic action. 



4. Distilled water caused a rapid contraction. A mixture of 

 distilled and boiled tap water gave the same result. In boiled 

 tap water the pigment cells contracted. Oxygenated distilled 

 water and boiled tap water maintained the pigment cells in a 

 normal expanded condition. It was the absence of oxygen and 

 not of the salts that caused the contraction. 



