2I 4 



Scientific Proceedings (115). 



calcium precipitants, (2) those which act on the gray matter only, 

 as creatin and strychnin. In order to determine possible similari- 

 ties and differences between mammalian nervous tissue and that 

 of one of the annelids, experiments were carried out on the nerve 

 cord of the earthworm, Lumbricus terrestris. In these experiments 

 the worm was decapitated, the anterior end of the preparation 

 pinned down and the nerve cord laid bare. The cord was then 

 dissected free for a distance of about 20 segments and the stimulat- 

 ing substances applied directly to it. Stimulation was indi- 

 cated by squirming movements of the posterior segments. 



Excitants of the first class, KC1, BaCl2, and Na3 citrate, each in 

 M/S concentration, gave marked excitation. Of the excitants of 

 the second class, camphor and strychnin, each in saturated solu- 

 tion, and picro toxin crystals, all yielded positive results within a 

 minute after application, but phenol, nicotin and creatin had no 

 effect, used either as crystals or in solution, ikf/64 tetra-ethylam- 

 monium chloride gave strong stimulation. 



The fact that excitants of the first class act on the annelid nerve 

 cord shows that the nerve processes reacting do not differ in this 

 respect from the axons of the myelinated fibers of mammals. 

 The action of the excitants of the second class exhibits two peculi- 

 arities ; the action is almost immediate, there is no latent period 

 of several minutes as in mammals and in squid 1 ; the fact that the 

 nerve cells of the earthworm are unaffected by phenol, nicotin 

 and creatin indicates a chemical organization different from that 

 obtaining in the neurones of higher forms in which stimulation 

 by these substances does take place. 



108 (1690) 



Observations on the specific exhaustion of cutaneous reactions. 



By GEORGE M. MACKENZIE and LOUIS B. BALDWIN. 



[From the Medical Clinic of the Presbyterian Hospital, 

 Columbia University, New York.] 



Cutaneous reactions in hypersensitive individuals are of two 

 quite distinct types. The reactions observed in patients with 

 hay fever or asthma and after sensitization by foreign serum 



1 Moore, A. R.. J. Gen. Physiol., 1919, i, 505. 



