PART II 



SPECIAL METHODS AND EXAMPLES 



CHAPTER XXIII 

 INJECTION— GELATIN MASSES (WARM) 



515. Introduction. Injection masses are composed of a coloured 

 substance called the colouring mass, and of a substance with which 

 that is combined called the vehicle. 



For instructions as to the operation of injecting, and the necessary 

 apparatus, see The Micrographic Dictionary, Rutherford's and 

 Schafer's Practical Histology, the treatises of Robin and Ranvier, 

 Beale's How to Work with the Microscope, the Lehrbuch der vergleichenden 

 Mikroscopischen Anatomic of Fol, and (for apparatus especially) the 

 article in the Enzyk. d. mik, Technik. For injections for the study of 

 the angiology of Vertebrates the practice of Robin and Ranvier may 

 safely by followed. For injections of Invertebrates (and indeed, for 

 vertebrates if it is desired to demonstrate the minute structure of 

 environing tissues at the same time as the distribution of vessels) masses 

 not containing gelatin are generally preferable to gelatin masses ; and 

 we would recommend as particularly convenient the Prussian blue 

 glycerin masses of Be ale. Glycerin masses have the great advantage 

 that they are used cold. 



All formulfe which only give opaque masses, or are only suitable for 

 coarse injections for naked eye study, have been suppressed. 



In § 809 is a section on injection of embryos. 



516. Vaso-dilators. In order that an injection may run freely 

 it is necessary that the vessels of the subject be in a relaxed state. 

 To this end the older anatomists used to wait until rigor mortis 

 had passed off before injecting. But it is evidently preferable in 

 the interest of the proper preservation of the tissues to inject 

 before rigor mortis has set in. Unfortunately, when this is done, 

 it is found that most injection masses — glycerin masses especially 

 — stimulate the contraction of the vessels, so that frequently it is 

 very difficult to get in the injection. In these cases it may be 

 advisable to use a vaso-dilator. The animal may be anicsthetised 

 with a mixture of ether and nitrite ofaniyl, and finally killed with 

 pure nitrite. Or, after killing before the injection mass is thrown 

 in. In any case it is advisable to add a little nitrite to the mass 

 just before using. The relaxing power is very great (see Oviatt 

 and Sargent, in St. Louis Med. Journ., 1886, p. 207 ; and Journ. 

 Roy. Mic Sac, 1887, p. 341). 



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