CHAPTER XXII. 



INJECTION GELATIN MASSES. 



475. Introduction. Injection masses are composed of a 

 coloured substance, technically termed the colouring mass, 

 and of a substance with which that is combined, technically 

 termed the vehicle. 



The following formulae are grouped mainly according to 

 the nature of the vehicle. The chief vehicles are gelatin and 

 glycerin. 



For injections made for the study of the angiology of Ver- 

 tebrates, the student will do well to follow the masterly prac- 

 tice of ROBIN and RANVIEK, consulting also, if necessary, 

 the excellent instructions given in BE ALE'S How to Work 

 with the Microscope, and in the Lehrbuch der vergleichenden 

 mikroskopischen Anatomic of FOL. For injections of Inverte- 

 brates (and, indeed, for Vertebrates if it is desired to demon- 

 strate the minute structure of environing tissues at the same 

 time as the distribution of vessels) glycerin masses are 

 generally preferable to gelatin masses ; and I would recom- 

 mend as particularly convenient the Prussian blue glycerin 

 masses of BE ALE. Glycerin masses have the great advantage 

 that they are used cold. 



All formulae which only give opaque masses, or are only 

 suitable for coarse injections for naked-eye study, have been 

 suppressed. 



476. Nitrite of Amyl as a Vaso-dilator. As stated above, 

 glycerin masses are certainly very convenient, and give very 

 good results from the scientific not from the aesthetic 

 point of view. They have a great defect for the injection 

 of fresh specimens that is, those in which rigor mortis has 

 not set in ; they stimulate the contraction of arteries. In 



