402 PRACTICAL HISTOLOGY. [xxxvut 



30. Blood Crystals (p. 120). If it be a guinea-pig or rat use 

 the defibrinated blood to obtain blood crystals. 



(a. ) Add water = haemoglobin crystals. 



(b. ) Add a small quantity of ether = haemoglobin crystals. 



(c.) Add amyl nitrite = methaemoglobin crystals. 



31. Blood Ehrlich's Granules. Perhaps it might be well to 

 give here a short resume of some of the results of Ehrlich and his 

 pupils. 1 Cover-glass preparations of the blood of different animals 

 are made, and they are either exposed to the air to dry (or they 

 may be carefully heated for several hours at 120 C. or passed 

 several times through the flame of a Bunsen-burner). On being 

 dried rapidly in the air, there is no coagulation of the cell-proteids, 

 and thus the cells retain their natural tendency to stain with dyes. 

 As haemoglobin is soluble in water it is better to use the dyes dis- 

 solved in glycerine. 



Leucocytes. The "granules" present in the protoplasm in the 

 varieties of white blood-corpuscles vary in their reaction to staining 

 reagents. Thus some are stained by what Ehrlich calls acidophile 

 dyes, of which eosin is one. It is not enough that the granules are 

 stained by one of these dyes. As a general rule, granules which are 

 stained by all the following solutions belong to his a-granulation 

 class and are " eosinophilous granules." 



'1. 



(3. 



Eosin in glycerine. 



Glycerine saturated with indulin. 



Concentrated watery solution of orange. 



The eosinophile cells (a granules) are always present in the leuco- 

 cytes of frog's blood, marrow of frog (numerous) very few in 

 spleen numerous also in the mesentery. In the rabbit they occur 

 in the blood, marrow (very numerous), spleen (few). 



Make a cover-glass preparation and dry it either at 120 C. 

 (several hours) or rapidly in the flame of a Bunsen. Stain for an 

 hour (or longer) with eosin-glycerine, wash in water, dry and mount 

 in balsam. Or stain cover-glass preparations in glycerine (30 cc.) 

 containing 2 grams each of aurantia, indulin, and eosin. Or a 

 saturated alcoholic solution of bluish-eosin may be used. 



If an eosin-indulin glycerine solution be used, the a-granulations 

 are purplish-red and the nuclei well stained bluish-black by the 

 indulin. 



The granular cells (" Mastzellen "), which occur so abundantly 

 in the connective tissue of the frog and some other animals, also 

 occur in the blood of the frog, triton, and tortoise. In man, accord- 

 ing to Ehrlich, they are found only pathologically. The granules 



1 Farbenanalyt. Unters. z. Histol. u. Klinik des Mutes, by P. Ehrlich, 

 Berlin, 1891. 



