440 CHARLES RUSSELL BARDEEN 



the neural groove and still more so during the formation of the 

 neural canal. Thus, for instance, in Experiment 4, in the neural 

 groove stage about 25 per cent appeared decidedly abnormal. As 

 the canal closed and the anlages of the head and tail appeared 

 about 80 per cent became abnormal in from and a quarter of these 

 appeared extremely distorted. In all of the experiments the 

 greater number of the larvae appeared abnormal during the latter 

 part of larval differentiation (table 1). The variety of abnormal 

 forms was very great. As might be expected, the earlier abnor- 

 malities of development make themselves manifest the more pro- 

 found are the deviations from normal structural form and, as a 

 rule, the earlier the larvae die. The alterations in structural 

 development manifest themselves in quite varied ways in differ- 

 ent larvse from a given lot of eggs fertilized by a given lot of 

 sperm. In one larva it is chiefly the cranial end that is affected, 

 in another chiefly the caudal end, in a third the trunk may be 

 relatively more affected than the head and tail. Internally the 

 effects may be seen chiefly in the central nervous system, in the 

 organs of special sense, in the vascular system or in the alimen- 

 tary canal. In the more extreme types the external form and 

 all of the internal organs are profoundly affected. 



In a previous paper, ('07), I have given a description of several 

 of these abnormal larvae and have summarized the effects noted. 

 I give here a brief review of this summary together with addi- 

 tional data derived from subsequent experiments. 



GENERAL EFFECTS 



In all specimens growth is decidedly retarded during larval 

 differentiation. If the larvae are hatched or are shaken from the 

 investing jelly they expand but shghtly while the normal larvae 

 increase very rapidly in size. Since this rapid expansion of the 

 normal larvae is known to be due largely to inhibition of water it 

 is fair to assume that this inhibition of water and the subsequent 

 secretion into the cavaties and into the connective tissues of the 

 body is in large part inhibited or altered in the experiment 

 specimens. 



