420 



T. H. MORGAN. 



worms present, showed a large percentage of abnormalities, 

 then the cause probably arose in the egg. 



The following tables give the data that I have collected. 

 The number of recorded cases is smaller than I could have 

 wished, but the evidence is all in one direction and fairly con- 

 vincing. The capsules were isolated and the worms collected 

 as soon as they crawled out. 



No. 



Conclusion. — In none of the capsules is there a prepon- 

 derance of abnormalities, nor does there seem to be any rela- 

 tion between the number of worms iu a capsule and the 

 presence or absence of wrongly united metameres. 



We must conclude that neither of the possible causes sug- 

 gested above is active in producing the abnormal embryos. 



We get no clue from these data as to any outside forces 

 producing the result ; and although we have not by any means 

 exhausted all the possibilities, still it seems not improbable 

 that in each particular case local internal conditions determine 

 the result. 



All of the commoner forms of abnormalities recorded for the 

 adult worms are also found in the embryo. This applies to 

 abnormalities in the anterior part of the body as well as in 

 other parts. There are more abnormalities in the tail end 

 than in the head end. 



A few typical abnormalities found in some of these embryos 

 (young worms just out of the capsule) are shown in PI. 42, 



