Abstract
In order to study the physiological effects of certain alkaloids upon some of the lower organisms, and to determine, if possible, whether there was any evidence of specificity of action in these forms, the following experiments were planned: (a) A study of the effects of caffein on some of the physiological and morphological processes of the young and adult forms of Planaria dorotocephala, an organism with relatively labile tissue; (b) a study of the effects of caffein, atropine, and pilocarpine on cleavage and on the embryonic development of one of the lower organisms in which differentiation is rapid enough to permit of modification under the influence of agents acting only for a short period of time.
The first series of experiments, (a), concerned themselves with a study of the effects of caffein upon oxygen consumption, carbon dioxide production, and head frequency in Planaria dorotocephala. A record of differential disintegration in high concentrations of caffein also indicated a differential susceptibility to this alkaloid. No specificity of action was found for caffein in this form, and both stimulation and inhibition were recorded in the studies made with head frequency and with respiration, the effect depending upon the concentration used, and the length of the period of exposure. 1
The experiments on early cleavage will be reported in this paper, and studies on differential modification of development in Arbacia punctuation will be reported in the following paper. In the study of the effects of various concentrations of alkaloids on the rate of early cleavage of Arbacia eggs, the following procedure was observed: Stock solutions of a 0.5% concentration were made up for each alkaloid. From these, further dilutions were made up such that concentrations ranged from 0.1 cc. to 10 cc. of stock solution per 100 cc. of sea water.
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