28 Journal of Comparative Neurology. 



II. Introduction. 



The present communication is presented merely as a record 

 of observations upon blood distribution in one particular animal 

 form, at a definite age, and in the normal cerebellum. To state 

 the matter in another form, questions regarding the compara- 

 tive arrangement in different species, in the same species at dif- 

 ferent ages, or under abnormal conditions are not included 

 within the scope of this paper. 



This record is based upon a series of observations extend- 

 ing over a period of ten years. The observations were first 

 made during the winter and spring of 1889, in preparations 

 made by myself Professor S. Calvin then pointed out from these 

 preparations that there was a difference in the blood supply of 

 the granule and molecular layers. From this point the obser- 

 vations were extended by the writer, and the arrangement pre- 

 sented in the summary to this paper was recognized as being 

 probably the true arrangement under the conditions mentioned 

 in the title. This arrangement has been demonstrated to class- 

 es and to private individuals year after year since 1889, in vari- 

 ous cats and with various injection masses. 



In what I propose to designate as a complete injection, a 

 term which will be explained later, the three classes of vessels 

 about to be described have always appeared. This fact having 

 been demonstrated again and again, it may be deemed unneces- 

 sary to state that it appears reasonably certain that this arrange- 

 ment is the true one, and that it may be demonstrated at any 

 time if the previously mentioned conditions are taken into con- 

 sideration, 



///. Methods, 



It is unnecessary to enter upon an extended discussion of 

 technique, inasmuch as no method was used which has not been 

 the common property of histologists for years. Nevertheless, 

 there is a necessity for outlining the technique. 



The logical basis for the technique of injecting blood cap- 

 illaries is as follows : We know from observing thin animal 



