54 EMPLOYMENT OF THE SPECTROSCOPE. 



the color appears the same in both. The illumination of the blood-solution and 

 the red wedge takes place from below by means of the light of a lamp. The 

 glass wedge is provided with a scale, and when the colors in the two halves of 

 the cylinder are alike the number on the wedge indicates the amount of hemo- 



flobin in terms of percentage of the normal blood; thus, for instance, the figure 

 o indicates that the examined blood contains 80 per cent, of the hemoglobin in 

 normal blood. 



(c) With the aid of the spectroscope Preyer found that a solution of 0.8 per 

 cent, of pxyhemoglobin in water i cm. thick yielded in addition to red and 

 yellow the first band of green in the spectroscope (Fig. 15, i). Of the blood to 

 be examined about 0.5 cu. cm. is taken and is diluted with water until the identical 

 of effect in the spectroscope is obtained. In addition to having the layers of fluid 

 equal thickness namely i cm. the width of the slit in the spectroscope and the dis- 

 tance between this and the vessel, as well as the intensity of the source of light 

 (stearin candle), must be the same. If k represents the amount of hemoglobin in 

 percentage that permits the passage of the green color (0.8 per cent.), and b the 

 volume of blood to be examined (about 0.5 cu. cm.), and w the amount of water 

 necessary for dilution, then x equals the amount of hemoglobin in the blood to 

 be examined expressed in percentage, that is x =k (w+b) : b. It is advantageous 

 to add a trace of potassic hydrate to the blood and to saturate it with carbon 

 monoxid. 



The amount of hemoglobin is in men 13.77 per cent, of the total 

 volume of blood, in women 12.59 per cent., in pregnant women with 

 progressive diminution from 12 to 9 per cent. According to Lichten- 

 stern and Winternitz the hemoglobin is most abundant in the blood 

 of the newborn, but this is no longer the case after the age of ten weeks. 

 Between six months and five years of age it is smallest in amount and 

 reaches its second maximum between twenty-one and forty-five years, 

 after which it falls again. The hemoglobin in female blood grows less 

 after the tenth year. The ingestion of food is followed by transitory 

 diminution in the amount of hemoglobin in consequence of the dilution 

 of the blood. 



The amount of hemoglobin in different animals is as follows: 9.7 per cent, in 

 the dog; 9.9 per cent, in cattle; 10.3 per cent, in sheep; 12.7 per cent, in swine; 

 13.1 per cent, in the horse, and from 1 6 to 17 per cent, in birds. 



In moist erythrocytes Hoppe-Seyler found the hemoglobin to con- 

 stitute 40.4 per cent, of all the organic elements, while in the dry cor- 

 puscles the amount was 95.5 per cent., the amount being smaller in the 

 nucleated corpuscles of animals. 



Pathological. A reduction in the amount of hemoglobin in the blood takes 

 place during convalescence from febrile diseases, as well as in the presence of 

 pulmonary tuberculosis, carcinoma, ulcer of the stomach, diseases of the heart, 

 chronic disease, chlorosis, leukemia, pernicious anemia, and in conjunction with 

 vigorous mercurial treatment for syphilis. In the presence of hunger the hemo- 

 globin is more resistant than the remaining solid elements of the blood. 



EMPLOYMENT OF THE SPECTROSCOPE FOR HEMOGLOBIN 



EXAMINATION. 



The spectroscope (Fig. 12 and Fig. 161) consists (i) of a tube A, having at 

 its peripheral extremity a slit S, which can be made larger and smaller. At the 

 other extremity is a double convex lens C, known as a collimator, so adjusted 

 that the slit is placed exactly at the focus of this lens. Light, from the sun or 

 a lamp, illuminating the slit, passes therefore in parallel lines through C. (2) The 

 prism P, by means of which parallel rays are refracted and broken up into the 

 spectral colors, r-v. An astronomic telescope, inverting the image, is directed 

 toward the spectrum r-v, which appears magnified from 6 to 8 times to the view 

 of the observer B with the aid of the telescope. (3) The tube O contains a delicate 

 scale M etched upon glass, and the image of which when illuminated is thrown 

 upon the surface of the prism, whence it is in turn reflected to the eye of the 



