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perimeuts were made on the eggs of Necturus. Moreover ray interest 

 in this form was deepened through the fact that Prof. Whitman 

 several years since called my attention to certain appearances which 

 seemed to indicate that the embryo of Necturus developed in an manner 

 strikingly similar to that of the Fish. 



The egg of Necturus is not so well suited for experimental work 

 as that of most of the Amphibia. The exovates are easily detached 

 and great care must be exercised in operating or the punctures give 

 rise to exovates which are so large that they interfere with normal 

 development. The method adopted was essentially similar to that 

 employed in the earlier experiments on other forms. 



Experiments. 



Series I. Twenty eggs in second cleavage stages were punctured 

 at the points indicated by the cross-lines in Fig. 1. Although the 

 eggs were handled with great care and the water frequently changed 

 and aerated but four reached the stage of neural folds. In these the 

 exovates occupied the positions shown in Figs. 4 — 7 inclusive. 



In one egg (Fig. 4) the exovates were found a short distance in 

 front of the transverse portion of the neural fold and both lying at 

 the rigth of a plane coinciding with the median sagittal plane of the 

 embryo. 



In a second egg, represented by Fig. 5, one of the exovates lies 

 in the outer margin of the neural fold, and at the level of the future 

 optiv vesicles, while the other lies farther away from the embryo but 

 nearer the level of its anterior end. Both of the exovates in this case 

 lie on the left of a plane which would coincide with the median sagittal 

 plane of the embryo. 



In a third egg (Fig. 6) the exovates both lie about the same 

 distance in front of the transverse portion of the neural fold and are 

 so situated that they would lie on either side of a plane coinciding 

 with the median sagittal plane of the embryo. 



In the fourth egg (Fig. 7) the exovates lie at different levels, the 

 smaller lying at the right of the body of the embryo and on a level 

 with the most anterior portion of the neural fold, the larger lies much 

 farther in front of the embryo and somewhat at the right of the median 

 plane of the embryo. 



While the percentage of eggs developing after puncture is very 

 small when compared with other Amphibian forms the results are 

 fairly uniform and indicate: 1) that the anterior end of the embryo 



