700 APPENDIX. 



Cells, oil-globules, free granular matter, and occasionally blood- 

 corpuscles and crystals of cholesterine are the principal constitu- 

 ents of the deposit obtained from ovarian fluid. _ Sometimes 

 masses of gelatinous or colloid matter are mixed with these ele- 

 ments. Minute fibres are sometimes observed crossing each 

 other in various directions, and contain in their meshes thus 

 formed, a transparent jelly filled with round or oval corpuscles. 

 (See Fig. 424.) The cells are either small, transparent, granular, 

 and non-nucleated, or large, opaque, and filled with oil-globules. 

 Fig. 376 represents fatty granules, mixed with plates of choles- 

 terine from an ovarian tumor, after Prof. Bennett. 



INJECTIONS. 



In studying the vascularity of tissues, injected specimens are 

 of great utility. The student should give some attention, there- 

 fore, to the practice of injecting the different organized structures 

 which he may desire to examine. Dr. Beale, in his admirable 

 little work on the application of the microscope to clinical medi- 

 cine — a work of which we have availed ourselves freely in the 

 construction of this chapter — gives the following practical direc- 

 tions as to the time, mode, &c., of making injections. 



" Generally, it may be remarked that we should not attempt 

 to inject while the rigor mortis lasts. Many days may in some 

 cases with advantage be allowed to elapse, particularly if the 

 weather is cold, while in warm weather we are compelled to in- 

 ject soon after death. As a general rule, the more delicate 

 the tissue, and the thinner the vessels, the sooner should the 

 injection be performed. Many of the lower animals, annelids, 

 moUusca, &c., and fishes, should be injected soon after death. 

 In making minute injections of the brain, only a short time 

 should be allowed to elapse after the death of the animal, before 

 the injection is commenced. Injections of the alimentary canal 

 of the higher animals should be performed early — not more than 

 a day or two after. 



" Minute injections of the papillpe of skin, particularly of the 

 fingers and toes, cannot be successfully made until the cuticle has 

 become somewhat softened by allowing the preparation to remain 

 in a damp cloth, or to soak in water, for some days. In these 

 situations the vessels are strong, and in their ordinaiy state, the 

 injection will not traverse them, in consequence of the cuticle 

 preventing their gradual distension by the injecting fluid. A 

 similar plan must be followed in making injections of the tongue, 

 and other parts where the epithelial covering is imusually dense, 

 and firmly adherent to the vascular surface beneath. 



"If the subject be a small animal, it is better to take out part 

 of the sternum, and fix the pipe in the aorta. If only part of an 

 animal is to be injected, the largest artery supplying the part 

 should be selected, and all the other open vessels may be tied or 

 stopped with the small forceps. 



