26 M. L. Shorey 
concerned, have demonstrated that an intimate relation exists 
between the life of a muscle and that of its motor nerves. And at 
least since 1851, when Weber described an abnormal calf embryo 
with the nervous system entirely wanting below the second dorsal 
vertebra and an accompanying loss of the corresponding muscles, 
there has been a tendency to believe that there is likewise a depend- 
ence in development. Other teratological cases in which a defect 
in the nervous system has been accompanied by a defect in the 
organs normally innervated by tbe missing nerves have been 
recorded, and the effect of the absence of the nerves in experi- 
ments in regeneration has been adduced as evidence in favor of 
such a view. It is obvious, however, that neither of these condi- 
tions can furnish conclusive evidence regarding developmental 
processes, for, in the case of monstrosities it is impossible to know 
the nature of the original lesion, and in regeneration, while there 
are doubtless similarities between it and normal development, it is 
evident that neither the conditions nor the processes can be iden- 
tical. 
Bardeen, in 1900, made careful observations on the relations 
between the myotomes and nerves at early stages of embryonic 
development, and from the fact that there is no apparent contact 
between the two until a considerable degree of differentiation has 
been reached concludes that early development is independent. 
To quote, “The early development of the nerves is one of passive 
independence, without any immediate relations to the myotomes.” 
But it seems to me that such evidence must be regarded as incon- 
clusive, for the fact that two organs are not in direct contact does 
not exclude the possibility that the one may influence the other. 
To reach decisive conclusions regarding the interdependence 
of two organs or tissues in development it is necessary to study the 
behavior of one in the absence of all possible effects from the other. 
This can be done only by destroying some portions of the develop- 
ing organism, or by removing the part to be studied to a controlled 
environment. Both these methods have been used in studying the 
relation of the nervous system to peripheral organs, but in most 
previous studies the object of the investigation was to discover 
the effect of the destruction of nervous tissue on the organ inner- 
