232 



A. T. CAMERON AND C. H. O DONOGHUE. 



inhaled in large quantities it may give rise to similar symptoms. 

 In some animals it produces violent and prolonged convulsions. 



The differences of behavior exhibited by frogs and mammals to 

 these drugs are shown by our results for the specific reflex that we 

 have studied to be even greater when the observations are extended 

 to include invertebrates. Although undoubtedly, as Cameron and 

 Sedziak found for frogs, the degree of reaction differs markedly 

 in different animals of the same species, and though our results 

 were in some cases affected by the length of time that the animals 

 were kept in the laboratory before they were tested, yet such 

 marked variations are shown that a distinct idiosyncrasy of differ- 

 ent species to the action of certain drugs is indicated. Thus cam- 

 phor was little or non-toxic and did not reveal the reflex in cottoids 

 and isopods ; to the frog it was toxic, but the reflex could not be 

 demonstrated ; while with crabs, blennids, and pipe-fish marked 

 responses to illumination changes were obtained with a varying 

 degree of toxicity. Camphor was non-toxic for one species of 

 shrimp, toxic but ineffective for a second, toxic and effective for a 

 third ; it gave marked reactions with the prawn employed by 

 Frohlich and Kreidl. 



Quantitative comparison of the different drugs is difficult, not 

 only on account of the different concentrations employed, but 

 chiefly because of our ignorance of the rate of absorption of these 

 drugs by different species and different sized specimens. The 

 results for phenol and benzene can perhaps b'e contrasted most 

 satisfactorily ; it would seem that benzene is slightly less toxic, but 

 it was of all the drugs employed the one most favorable for the 

 production of the retinal reflex. It is to be noted that in at least 

 one species (the isopods examined) for which camphor was non- 

 toxic benzene was distinctly toxic. 



It would seem that in most of the species studied benzene pro- 

 duces on the central nervous system an action distinctly compara- 

 ble to the typical paralyzing action of phenol and camphor, and 

 relatively much greater than that it produces in mammals. 



Dr. Mary Rathbun, of the U. S. National Museum, kindly 

 identified the species of shrimps employed, and Dr. B. W. Ever- 

 mann, of the California Academy of Sciences, the blennids. 



