8 HENRY MCELDERRY KNOWER 



sive title, * ' Development of Lymphatics in Anura ' ' ; but they 

 do present the chief serious attempt to date to supplement 

 and complete the descriptions of Hoyer and my brief state- 

 ments in 1905, 1908, 1913-1914 for the development of the 

 system in various frogs, studied by injection. This author's 

 fair minded discussions and his numerous models which sup- 

 ply many illustrations are certainly among the best examples 

 of thorough workmanship and skill by the method of recon- 

 struction. 



But injections of lymphatics in frog embryos reveal im- 

 portant differences in facts from Kampmeier's findings for 

 the development of the system in the toad, and leave us in 

 fundamental disagreement with his conclusions. The develop- 

 ment of the system as described for the toad is certainly not 

 characteristic of that in the majority of the Anura. The same 

 reservation may be made here for the results of Goda ('27) 

 on a Japanese toad, presented in models in which the recon- 

 structions do not agree in important features with those for 

 the other toad studied by Kampmeier. 



Though the numerous criticisms referred to above appear 

 to amply dispose of the usefulness of the reconstruction 

 method, repetition here seems called for, in view of the con- 

 tinued insistence on the value of the method in the recent 

 contributions on the development of lymphatics considered in 

 this paper. 



This brief introduction should then suffice to explain why in- 

 jections have formed the main dependence for the studies on 

 lymphatics reported in the present contribution; not only to 

 avoid the objections noted above as to the unreliability and 

 subjective nature of reconstructing such vessels from tissue 

 spaces in sections of fixed material ; but also because of the 

 great positive advantages offered by injected specimens. 



For every model of a system reconstructed from sections 

 in a single embryo it is possible to obtain, in far less time, 

 many injected specimens of the same stage ; and satisfactory 

 injections not only give the main trunks, but also many details 

 of the system examined and of related vessels not otherwise 



