ON THE EXPERIMENTAL PRODUCTION OF EDEMA IN 

 LARVAL AND ADULT ANURA. 



By CHARLES F. W. McCLURE. 



{From the Laboratory of Comparative Anatomy, Princeton University, Princeton.) 

 (Received for publication, November 5, 1918.) 



Edematous frog larvte are among the commonest types of ab- 

 normalities which can be produced by experimental means. When 

 ova of the two- or four-celled stage are placed in solutions of potas- 

 sium cyanide, acetone, butyric acid, or ethyl alcohol for from 12 to 

 24 hours, and then subsequently developed in tap water, an edema- 

 tous condition of the body frequently, though not always, results. 

 Hertwigi has produced such larvae by exposing early cleavage stages 

 to the influence of radium. An edematous condition of the body 

 also occasionally results when ova are allowed to develop in direct 

 sunlight in the laboratory and may even be met with among the 

 controls. The life of such larvae is relatively short. 



The edematous frog larvae thus far observed by the writer can be 

 grouped into two main types: Type 1, in which, with the exception of 

 their general edematous condition, the frog larvae appear externally 

 to be otherwise normally developed; Type 2, in which some marked 

 abnormality, especially of the head region and vascular system, 

 usually accompanies an edematous condition of the body. 



All the larvae referred to in this paper were in the stage at which 

 the pronephros acts as the functional kidney and in which the meso- 

 nephros is either not at all developed, or is represented only by its 

 earliest anlage. 



An examination of serial sections of a large number of both types 

 of edematous frog larvae shows that in all cases, and without exception, 

 there is a marked deficiency evident in the development of certain 

 specified tubules in the pronephros. Reconstructions after the method 

 of Born clearly indicate that this deficiency is associated with the 



^ Hertwig, O., Arch. mikr. Anat., 2te Abt., 1911, Ixxvii, 1 (see Tables II and 

 III for examples of edematous frog larvae) . 



261 



