No. 643] SEROLOGICAL PHENOMENA 



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gland, or an environmental modification of it generation 

 after generation, we might have in its waxing or waning 

 output the excitant necessary for germinal changes which 

 become outwardly expressed as a series of orthogenetic 

 changes. That this suggestion of endocrinal influence on 

 the germ is not so far fetched as would appear at first 

 sight, is evident, I think, when we recall that certain of 

 the conditions which can be induced in individuals by 

 experimental or pathological endocrinal upsets are known 

 to occur also as congenital defects which are inheritable. 

 For example, short-fingeredness (brachydactyly) may be 

 induced after birth by too much pituitary secretion, but 

 such a condition is also well knowm as a congenital defect 

 which is hereditary-. In the latter case, is it more reason- 

 able to suppose that the short-fingeredness, could we 

 trace it back into the germ, is really represented by a 

 factor that has to do primarily with the finger or with a 

 factor directly concerned in some way with the pituitary 

 body? And did hypertrophy of the pituitary body origi- 

 nally induce the heritable type of brachydactyly ? We do 

 not know, but the parallelism of tlic two cuKlitions, it 

 seems to me is highly suggestive. 



And let us glance for a minute at otic of the well- 

 knowm studies on orthogenesis; that of Rutliven'' on the 

 variations of scutollatioii in the garter snakes. In his 

 own words: 



... it seems to mo that the iiKXst tenable hypothesis of the evolu- 

 tion of the genus Thamnophis is that it originated and became dif- 

 ferentiated into four main groups in northern Mexico. From this 

 region the groups radiated in all directions, but principally to the 

 northward, and wherever they entered different regions the changed 

 environmental conditions acted as an unfavorable stimulus which 

 retarded growth, and differentiated the groups into dwarfed forms. 



And in another place he generalizes as follows: 

 (1) That the maximum scutellation and size in the genus Tlmm- 

 nophis occurs in the center of dispersal, and the forms that have 

 been produced in the history of its migration have been formed 

 principally by dwarfing and by a reduction in scutellation; (2) 

 that the variation in the number of scales in the different series is 



