464 Eben Clayton Hill. 



would greatly simplify the later research on this gland in man. 

 Such, however, was not the case and results obtained in late years 

 by various investigators tend to disprove the theory that the general 

 structure and blood supply of the organs of lower mammals is al- 

 ways similar in detail to that in man. 



Text books have too frequently adopted the results obtained from 

 investigations on dogs, pigs or other mammals and have incorporated 

 the illustrations and descriptions without specifying that such re- 

 sults have not as yet been verified for man. 



So very marked are the differences of the gross structure and 

 blood supply of the human testis as compared with that of the pig 

 that the study of the human testis was practically an entirely new 

 research. The methods used were similar and will be briefly de- 

 tailed, but in no other way did a study of the testis of the pig 

 aid in solving the problem of the blood supply of the male sex 

 gland of man. 



Professor MacCallum, of the pathological department, very kindly 

 placed at my disposal the testes from autopsy subjects, and for 

 this courtesy I desire to express my thanks. These specimens were 

 usually brought to the anatomical laboratory within twenty-four 

 hours after death and were in excellent condition. Professor Mall 

 and Professor Brodel also aided me in obtaining several valuable 

 specimens of human embryonic testes, and to them I wish to ex- 

 press my appreciation. Embryonic material in fit condition for 

 injection is most difficult to obtain, and I regret that a series of 

 human embryonic testes could not be injected similar to that of 

 the pig.^ 



My injections were made with either India ink or celloidin. 

 The detailed technique of these injections is given in my separate 

 publication^ on clearing methods, but the following improvements 

 should also be noted: The gland or organ under investigation must 

 be fresh and must contain no clotted blood. Warm, normal saline 



'Hill, E. C. On the Gross Developuient and Vascularization of the Testis, 

 Am. Jour. Anat., Vol. 6, No. 4. 



«Hill, E. C. On the Schultze Clearing Method as Used in the Anat. Lab. 

 of the Johns Hopkins University. J. H. H. Bull., Vol. 17, No. 181. 



