THE H^EMOCHROMOMETER. 53 



and use iodized serum in place of urine. The ordinary per cent, solution 

 of common salt in water will also answer sufficiently well. 



Kecent investigations, such as those conducted by Drs. Cut- 

 ter and Bradford, of Boston, have established that there is 

 great variation in the number of globules of an individual, de- 

 pending on various causes, such as the locality from which the 

 blood is drawn, the loss of fluids, as by diarrhoea, sweating, 

 increased urinary secretion, etc., and even the period of the 

 day, week, or year. These general conclusions have also been 

 sustained by Hayem, of Paris, in researches which are still 

 being prosecuted. 



When one further considers that we have no definite stand- 

 ard of comparison ; that the instrument is apt to be imperfect ; 

 that there is a liability of errors to the amount of 10 per cent.; 

 that skill and practice are required in manipulation, it is by no 

 means difficult to see that the haematometer is not calculated 

 at present to introduce much scientific precision into medicine, 

 unless the most extraordinary precautions are taken in every 

 case, and these all duly noted. 



Blood crystals. The pigment of the blood occurs usually 

 in an amorphous form, and is called haematine. The brownish 

 red needles found in extravasated blood are known as haema- 

 toidine. 



Haemoglobin also occurs in most mammalian blood, and is 

 deposited under the form of rhombic plates. It is estimated 

 that about 125 grammes are present in the blood of a healthy 

 adult. 



THE HJEMOCHROMOMETER. 



According to Mantegazza and others, richness in haemoglo- 

 bin indicates a corresponding richness in red corpuscles, and 

 any special depth of color in the blood may be regarded as im- 

 plying a certain given number of red corpuscles to the cubic 

 millimetre. While this ratio appears to hold true in health, it 

 fails in disease. Thus, a condition which we recognize as anae- 

 mia may be almost wholly due to a loss of haemoglobin in the 

 corpuscle, or an actual loss of red corpuscles, together with a 

 diminished amount of haemoglobin in those that remain. In 

 the cachexia of cancer the number of the corpuscles may be 

 sustained, but their haemoglobin diminished. In diabetes mel- 



