Susceptibility in amphibian development

Abstract

In a recent paper Mr. H. Graham Cannon (1) has presented data on susceptibility in amphibian development, some of which are in disagreement with Bellamy’s results (2, 3), and has also criticised the application of the physiological gradient conception to the higher animals. In response to inquiry whether the ‘Proceedings of the Royal Society’ were open to us if re-examination of contested points should make further discussion desirable, Dr. E. W. MacBride has very kindly consented to communicate to the Society a statement of our results and our position. We wish to express our appreciation of this courtesy and of the courtesy of the Royal Society in admitting this communication. During the amphibian breeding season of the present year (1923) we have worked with four genera, Amblystoma tigrinum, Bufo americanus, Corophilus nigritus , and Rana pipiens , with reference to the points disputed by Mr. Cannon. The work was in part repetition of earlier work and in part new. The present paper includes results of this work so far as they concern points at issue: we have also taken the opportunity to clear up certain obscurities and to supply certain omissions to which Mr. Cannon has kindly called attention. And finally, in the hope of avoiding to some extent future misunderstanding of our views we have attempted a brief statement of the chief results of the susceptibility method and of the conclusions to which it has led.