32 MANUAL OF HISTOLOGY. 



ing of the vessels may be accomplished in one of two ways : 

 either by forcing in the fluid with a syringe or by the pressure 

 of a column of water. The syringe is the simplest, but requires 

 practice and skill in manipulation. 



Having inserted the canula into the artery, the kidney may 

 be entirely filled with either the red or blue injecting liquid. 

 When the organ is seen to be swollen, tense, and well colored 

 the vessels must be tied off, and the kidney placed in a freez- 

 ing mixture until the gelatine has set. When this is accom- 

 plished, the organ should be cut into small pieces, and placed 

 first in a weak solution of alcohol (seventy per cent, or less), 

 and the strength of the alcohol gradually increased until the 

 specimen is sufficiently hard for cutting. The object of using 

 weak alcohol is to prevent too great shrinkage of the gelatine. 

 If two colors are used, it is impossible to tell beforehand how 

 much fluid will be necessary to fill the arterial arid venous sys- 

 tems, and not have the one encroach on the other. For an 

 ordinary kidney, about 250 c.c. of the injecting liquid should 

 be prepared to fill the arterial vessels, and nearly double to 

 fill the veins. The following rules must be observed in inject- 

 ing : keep the gelatine solutions and the organ as nearly as 

 possible at the same temperature. Immerse the organ in warm 

 water during the process. Avoid the entrance of air into the 

 canula when connecting the syringe. Inject slowly, and give 

 the fluid time to work its way into the minute capillary rami- 

 fications. 



The above rules can be applied to any organ, with such 

 modifications as will suggest themselves to the operator. 



BIBLIOGRAPHY. 



KLEIN. Handbook of the Physiological Laboratory. Edited by Sanderson. Vol. I. 



1873. 



BDSCH. Arch. f. Mikroskop. Anat. XIV. 1877. 



NORRIS and SHAKESPEARE. American Journal of the Medical Sciences, Oct., 1877. 

 KENAUT. Archives de physiol. 2me Se'rie, T. IV. 1877. 

 SCIIAEFER. Histology and the Microscope. Philadelphia, 1877. 

 THIN. Practical Histology. London, 1877. 

 WENDT. Ueber die Hardersche Druse, etc. Strassburg, 1877. 

 KANVIER. Traite technique d'histologie. Paris, 1877-8. 

 BROESICKE, J. Med. Centralblatt. 46. 1878. 



