146 PROCEEDINGS OF THE AMERICAN ACADEMY. 



Summary. 



From the facts obtained in the foregoing experiments it may be 

 inferred that alkaloids, such as atropine, pilocarpine, morphine, digi- 

 talin, strychnine or quinine, when present in sea-water in very small 

 quantities, produce no influence upon the developing eggs of Toxop- 

 neustes variegatus, and become effective only with the approach to a 

 certain concentration, which is different for the different alkaloids and 

 also for different lots of eggs. The length of time from the moment 

 the eggs are subjected to the influence of these alkaloids till the effect 

 becomes noticeable differs, of course, for the various alkaloids, but as 

 a rule the stronger the solution the earlier in the developmental process 

 does its effect become pronounced. In the weaker solutions the effect 

 is seen only in later stages, the earlier stages (segmentation) remaining 

 unaffected. The increasing influence is not due to a gradual concen- 

 tration of the originally weak solution through evaporation of the 

 water, as was determined by measuring the volume of water in dishes 

 before and after the experiment, but seems rather to be the result of 

 accumulated effects due to a prolonged action of the poison. In solu- 

 tions which were effective and yet not sufficiently strong to check 

 noticeably the development of the eggs in the earlier stages, the larvae 

 as a rule were smaller than the normal ones. 



Pilocarpine does not hasten the development of eggs of Toxopneustes 

 variegatus, and larvae developing in pilocarpine solutions are either 

 of the normal size or else they are smaller than the normal ones, depend- 

 ing upon the strength of the solution and the lot of eggs. Pilocarpine 

 and atropine mixed in various proportions do not, in my experience, 

 neutralize each other's action, but the depressing effect predominates. 



Papers Cited. 

 Matthews, A. P. 



-.01. Action of Pilocarpine and Atropine on Embryos. Amer. Jour. 

 Physiol., Vol. 6, pp. 207-215. 

 Sollman, T. 



:04. Simultaneous Action of Pilocarpine and Atropine. Amer. 

 Jour. Physiol., Vol. 10, pp. 352-361. 



