ANATOMICAL PROBLEMS BEARING UPON EVOLUTION. 13 



refer to this subject, and to inquire what bearing the 

 occurrence of anatomical variations may be said to have 

 upon the general problem. 



Anatomists, from a minute study of a single species, 

 are tolerably familiar with the extent and importance of 

 these variations from the normal. We are all aware how 

 the monotony of the anatomist's day is varied by the 

 occasional mild excitement caused by the occurrence of 

 an abnormality. It is gravely handled by the professor, 

 examined by the demonstrators, and enthusiastically 

 dissected by the student, until eventually the excitement 

 subsides and the specimen is gone. 



Variations may be gross or refined, teratological or 

 anatomical. If any philosophical significance attaches to 

 the occurrence of variations, if they are stepping-stones in 

 the pathway of evolution, teratological variations of such 

 a kind as to interfere with the vital functions of the indi- 

 vidual, might be expected to disappear through want of 

 inheritance. 



Even gross variations can, however, be traced, as a 

 rule, to an excess or arrest of development along the usual 

 lines. They thus have a distinct value (and this is their 

 only scientific value, in my opinion) in corroborating and 

 confirming the path of development of the organ in 

 question (e.g., cleft palate, spina bifida). 



The development of the kidney and ureter has been in 

 recent years subjected to fresh study, with the result that 

 the accepted view of their formation has been doubted. 

 Such a teratological example as a rudimentary kidney and 

 a separate rudimentary ureter, lends support to the 

 orthodox view of the formation of the two organs from 

 separate elements. 



The occurrence of variations great and small alike 

 raises some unanswerable questions. 



