244 W - J- CROZIER. 



vaguely. Ventralward contraction, especially at the anterior end, 

 was always produced by nicotine, camphor, phenol, resorcin, and 

 caffeine. 



CHEMICAL DIFFERENTIATION. 



It is of interest to make note of certain facts bearing upon the 

 question of phylogenetic neuromuscular differentiation, from the 

 standpoint of reactivity to drugs. 



The larvae used agree in showing that the following instances 

 exert a very definite neuromuscular excitation evidenced by 

 spontaneous writhings, often of definite pattern, or by temporarily 

 heightened responsiveness, or both : 



* nicotine (i -.500) 



* picrotoxin ( i 1240) 



* camphor (saturated) 



* pilocarpine (i :iso) 



* adrenaline (i :iooo) 



phenol ( i 12000) 



* resorcin ( i : 1000) 



caffeine (saturated solution ; i :2oo, without 



effect) 



* tetraethylammonium hydroxide (m/64) 

 chloroform (1/3 saturated) 



* atropine ( i :soo) 



strychnine (i :ioo) 



* (Especially exciting.) 



Creatine, m/8, gave only slight temporary paralysis, probably 

 not specific. 



These facts suggest obvious differences when the behavior of 

 the caterpillars is compared with that of other invertebrates. The 

 action of atropine, and the relative lack of effectiveness of strych- 

 nine, point to parallelisms with conditions in ccelenterates, 14 rather 

 than with forms closer akin. Crayfish injected with strychnine 

 fail to yield evidence of "reversal" in the use of muscle groups, 

 and atropine -has a marked effect in stimulating the thoracic 

 ganglia. But in how far the peculiarities here revealed are arthro- 

 podan characteristics cannot as yet be said. 



In comparing a series of larvse, such as the Saniias and lo, one 

 is struck by the fact that the lo caterpillar, provided with urticant 



i* Moore, A. R., Proc. Nat. Acad. Sci., Vol. III., p. 598, 1917. 



