RECAPITULATION 207 



head. But the first suggestion seems the more 

 probable, as two rights or two lefts would not be 

 symmetrical. Supposing the head and body not 

 properly to belong to each other, one being reversed 

 and one normal, we can in a way understand why 

 the dorsal fin does not form the usual connexion with 

 the edge of the head, because the determinants would 

 not be in the normal intimate relation to each other. 

 In thus writing of reversed and normal it must be 

 understood that the former word does not mean 

 merely turned over, for in that case right side of the 

 body would be joined to the left side of the head, and 

 the dorsal fin would be next to the ventral side of the 

 head, which is not the case. What is meant is that a 

 left side of the body which is normally pigmented is 

 joined to a left side of the head which instead of 

 having both eyes has neither, the two eyes being on 

 the right side of the head which is joined to the right 

 side of the body, and this is normal and unpigmented. 

 The dorsal fin belonging to the normal sinistral body 

 would therefore have a congenital tendency in the 

 metamorphosis to unite with the head on the outer 

 side of the original lower or right eye after it has 

 moved to the left side. Actually, however, in this 

 abnormal specimen it finds itself on the outer side of 

 the left eye which has passed to the right side, and it 

 has no tendency to unite with this part of the head. 

 At the same time it has no tendency to bend over at 

 an angle to reach the outer side of the right eye, and 

 therefore it grows directly forward without attach- 

 ment to the head at all. 



It will be seen, therefore, that what is changed in 

 relative position in these mutations is not the actual 

 parts of the body, but merely the characters of those 



