AUTHOR’S ABSTRACI OF THIS PAPER ISSUED 
BY THE BIBLIOGRAPHIC SERVICE, MARCH 30 
EXPERIMENTS ON THE DEVELOPMENT OF THE 
SHOULDER GIRDLE AND THE ANTERIOR LIMB 
OF AMBLYSTOMA PUNCTATUM 
S. R. DETWILER 
From the Osborn Zoélogical Laboratory, Yale University 
THIRTY-THREE FIGURES 
1. INTRODUCTION 
Experiments on the transplantation of limbs have been ecar- 
ried on in connection with various problems: a) on the develop- 
ment of nerves (Banchi, ’05; Braus, ’05, and Harrison, ’07); 
b) on the question of orientation and laterality (Harrison, ’17); 
c) on the question of the development of the shoulder girdle 
(Braus, ’09), the rudiment of which is intimately bound up with 
that of the limb. It is with these last experiments that we are 
particularly concerned, since they have a more specific bearing 
on the results of the investigations set forth in this paper. 
Although the intimacy of these two systems—shoulder girdle 
and limb—during development and differentiation led Wieder- 
sheim (’92) to conclude. that girdle formation is possible only 
under the formative influence of the free extremity, the experi- 
ments of Braus showed, in part, the lack of interdependence of 
these systems. Braus found that the removal of the fore-limb 
buds of Bombinator included the tissue from which the central 
or glenoid portion of the girdle develops, and that only the 
distal parts—suprascapula and epicoracoid—were formed fol- 
lowing such an operation. The differentiation of these isolated 
girdle elements from unremoved blastema in the absence of the 
developing appendage demonstrated their independence of the 
free extremity. Confirmation of this observation was made on 
Amblystoma by Harrison (718), who found, however, that as 
development proceeded these two separate distal elements gradu- 
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