. The action of various pharmacological and other chemical agents on the chromatophores of the brook trout Salvelinus fontinalis Mitchill. Chromatophores; Trout. 170 JOHN N. LOWE decrease its irritability; 2) on the nerve endings leading from the ganglia controlling the pigment cells; 3) on the central nervous system. I have no direct evidence to offer which will enable us to determine which of these or combination of these three fac- tors are operative in the action of the drugs on the pigment cell, for I was unable to separate the nervous and pigment cell tissues for experimental purposes. I
. The action of various pharmacological and other chemical agents on the chromatophores of the brook trout Salvelinus fontinalis Mitchill. Chromatophores; Trout. 170 JOHN N. LOWE decrease its irritability; 2) on the nerve endings leading from the ganglia controlling the pigment cells; 3) on the central nervous system. I have no direct evidence to offer which will enable us to determine which of these or combination of these three fac- tors are operative in the action of the drugs on the pigment cell, for I was unable to separate the nervous and pigment cell tissues for experimental purposes. It is obvious that large doses have no selective action. At certain optimal concentra- tions all the drugs show a selective action on the pigment cells or their controlling mechanism. This selective action of drugs on the mechanisms of the pigment cells will further our knowl- edge as to their Fig. 1 A normal brook trout embryo showing the general alignment of (he body. In interpreting my results I have given special emphasis to their relation in a comparative way to the observations of other observers on various vertebrate and invertebrate tissues. This comparative method makes the results easier of interpretation and is less liable to lead to an erroneous conclusion. The drugs used were all of Merck's manufacture. They were dissolved in oxygenated distilled water. The stock solutions were made up from per cent to per cent. Dilutions were made from these solutions. The experiments were carried on in Syracuse watch glasses in 10 cc. of the solution. These re- sults were checked by experiments in small stender dishes of 50 cc. capacity. The conclusions are based on experiments re- peated ten times in 1913 and again in 1914 another series of ten was tried. Five to ten animals were used at one time in each dilution. The trout embryos used were from four days to two weeks after hatching. In no case were the individuals of the different ages mixed. 2 Figures 1, 2,
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