208 REYNOLD A. SPAETH 



Under these circumstances the melanophores always contracted." 

 Control cells under identical sealed jars, remained expanded. 



I have also exposed contracted melanophores of Fundulus in a 

 contracting mixture of 4 parts of O.l'N NaCl + 1 part 0.1 N KCl 

 to the vapors of amyl nitrite, using the same technique as in the 

 trials with ether and alcohol. All these melanophores expanded 

 promptly whereas control cells in the same contracting mixture, 

 under a second sealed bell-jar, showed no change. 



Weak solutions of atropine or atropine sulphate (0.00025 M 

 in 0.1 N NaCl) produce a prompt expansion of the melanophores 

 in Fundulus. The dilating action of this alkaloid ujion the pupil 

 is a familiar physiological phenomenon. 



Lieben ('06) found that in R, temporaria, subcutaneous injec- 

 tions of adrenalin produced a complete contraction of the melano- 

 phores in 15 to 20 minutes. The local application of adrenalin 

 upon the swimming web also produced a contraction. These 

 contractions Lieben believed to be independent of the constrict- 

 ing action of the adrenalin upon the blood vessels. When the 

 melanophores of Fundulus are immersed in solutions of adrenalin 

 hydrochloride of different concentrations they invariably con- 

 tract. Even at a dilution of one ])art to one million (in 0.1 N 

 NaCl) a contraction appears, though not always in all the melan- 

 ophores of a single scale. 



From the foregoing obser\'ations it appears that certain or- 

 ganic substances which typically produce contractions in smooth 

 muscle, cause a contraction in the melanophores of Fundulus. 

 Reciprocally, certain other organic substances which produce an 

 expansion or relaxation in isolated smooth muscle, produce an 

 expansion in the melanophores of Funduhis. 



' 'rii(j cuiitracticjn dopcud.s, liuwevcr, upuii tlic, auiuunt ol organic tiuid in tlu' 

 Syracuse dish. Under the conditions of these experiments, 3 to 5 drops pro- 

 duced a contraction. Larger amounts inhibited the contraction and produced 

 a narcosis. This became evident when the cells were removed from the bell 

 jars, for a transient contraction appeared, the effect of the dilute stimulus. 



* A Parke-Davis preparation of adrenalin hydrochloride 1 : 1000 in i)hysio- 

 logical salt solution was used as the starting j)oint in these experiments. This 

 was diluted with 0.1 N NaCl to the required concentration. 



