1882.] 



MICKOSCOPICAL JOUKNAL. 



187 



algae. The examination of blood 

 with the microspectroscope is of great 

 importance in legal proceedings. To 

 Prof. Stokes we are indebted for some 

 very elaborate investigations of the 

 coloring matter of blood. His results 

 were published in the Proceedings of 

 the Royal Society^ 1864. He found 

 that when blood was treated with 

 some^ reducing agent, such as a solu- 

 tion of ferrous sulphate containing 

 tartaric acid, or stannous chloride, 

 the color was changed from a bright 

 scarlet to a purple. This change 

 in color is accompanied by a modifi- 

 cation of the spectrum, the two bands 

 characteristic of oxygenated blood 

 being replaced by a single band oc- 

 cupying a position between the places 

 which they held. He named the 

 bright-red constituent scarlet cruorine, 

 and the other purple cruorine. When 

 the reduced or deoxydized blood is 

 shaken up with air the scarlet cruor- 

 ine is again formed, and shows the 

 two-band spectrum as before. These 

 changes are quite characteristic of 

 blood, but there are still others, 

 brought about by acting upon blood 

 with acid and alcohol, which render 

 spectroscopic examination still more 

 conclusive of the nature of the fluid 

 under examination. 



The delicacy of the test for blood 

 by the microspectroscope is quite re- 

 markable. A scarcely visible stain 

 upon a piece of white paper, not more 

 than YoTo'ooT <^f ^ grain, will show 

 the bands, but it is more satisfactory 

 to work with solutions of blood. A 

 quantity not greater than j^g^ of a 

 grain of blood in a cell measuring yV 

 of an inch in diameter by half an inch 

 deep will show the bands very clearly. 



A New Form of Constant Pres- 

 sure Injection Apparatus.* 



BY PROF. WILLIAM LIBBEY, JR. 



In studying the circulatory system, 

 the means of injection are an indis- 



* Read before the Section of Histology and 

 Microscopy of the A. A. A. S., at Montreal. 



pensable aid. This operation can be 

 performed in several different ways, 

 but the most satisfactory method 

 would, of course, be that which would 

 in the simplest manner utilize the 

 materials used, and at the same time 

 place them under the most perfect 

 control of the operator. 



In the piece of apparatus described 

 below, the wants of my laboratory 

 have been especially consulted, and 

 the object kept in view was the con- 

 struction of a machine which would 

 perform the most delicate injections 

 in a satisfactory manner. 



In a sense, it may be said that this 

 object has been realized ; but, as the 

 element of good judgment can never 

 be made part of a machine, the de- 

 gree of success will still be in propor- 

 tion to the skill in manipulation. 



All such machines must have a 

 certain similarity in their construc- 

 tion, but may differ essentially in the 

 arrangement of their several parts, 

 and for this reason no great original- 

 ity is claimed for the apparatus ; the 

 method of the operation in the ma- 

 chine under consideration is as fol- 

 lows : — 



We will suppose the animal, or 

 organ, to be injected to have been 

 prepared as is usual, and placed over 

 a water-bath arranged to secure a 

 proper degree of temperature dur- 

 ing the operation ; the injection- 

 mass having been also previously 

 prepared and placed in a three- 

 mouthed Woulffs-bottle (prepared as 

 a wash-bottle with closely-fitting 

 rubber corks), which should, of 

 course, be placed over a water-bath 

 to keep the mass liquid. 



The source of the power utilized is 

 twenty pounds of mercury, which, by 

 changing position from a higher to a 

 lower level, forces the air out of one 

 of two globular glass filtering funnels 

 alternately, as one is placed below or 

 raised above the level of the other, 

 which should be kept stationary. 

 These two filtering funnels are sup- 

 ported on iron rings with clamps 

 which can be attached to two iron 



