46 CHARLES It. STOCKARD 



the same body fluids? This question presents considerable 

 difficulties, yet there are possible answers. It may be re- 

 called, for example, that in embryonic development compar- 

 able growth stages of limb and axial skeleton are reached at 

 different embryonic periods. An endocrine disturbance modi- 

 fying' limb growth may possibly occur temporarily during a 

 critical period in the development of the limb and then dis- 

 appear, leaving a normal environment during the critical 

 stage of origin for the cartilages of the basicranium and the 

 vertebral column. Temporary endocrinal and chemical dis- 

 turbances are of so common occurrence during postnatal life 

 that it is logical to suppose that during embryonic existence 

 similar disturbances may occur for short periods and then 

 disappear. If embryonic distortions of endocrine glands are 

 responsible for the deformed legs of the bassethound and 

 dachshund, such glandular disturbances are not detectable in 

 later life, since, as we shall see in the histological section of 

 this study, the endocrine glands of mature individuals of 

 these two breeds show no decided deviations from the normal 

 type. Therefore, if a disturbance in endocrine balance or 

 quality occurs during a brief embryonic period to modify 

 limb skeletons, it becomes ineffective during later embryonic 

 periods and completely disappears, leaving no mark that can 

 be found in the endocrine glands of the adult. 



The simple examination of these dogs themselves cannot 

 furnish a very satisfactory basis for determining whether 

 the short legs are primarily genetic in origin or are a sec- 

 ondary reaction to a peculiar endocrine condition, which may 

 be in itself primarily genetic. With the hope of arriving at 

 a more satisfactory understanding, an extensive study has 

 been made of the inheritance of short, achondroplasic le^s 

 as a contrasted condition to the normal long leg. Three 

 breeds of dogs witli typical short achondroplasic legs have 

 been employed: the bassethound, dachshund and Pekingese. 

 The bassethound, a normal sized foxhound typed dog with 

 very short twisted legs, and the well-known dachshund, a 

 dwarf hound typed dog, are both European breeds and may 



