38 MANUAL OF HISTOLOGY. 



l^ulth it has reached 6,000,000 and over. Under ordinary cir- 

 cunisianees 4,500,000 is thought to argue a fair bodily condi- 

 tion (Keyes). 



Quite recently Hayem has given an instance where the number was reduced 

 to 800,000. This extraordinary state he has called aglobulie intense ; the name 

 (tr/lobxlie extreme was given to a condition observed on another occasion where 

 he counted only 450,000 corpuscles. 



The Uood-globules in an indifferent fluid. -In order to get 

 a proper conception of the various influences that act upon the 

 red corpuscles, so as to alter their form, size, and internal 

 appearance, it is essential to subject them to some of the more 

 common, such as water, acids, alkalies, electricity, etc. In 

 no other way can the student appreciate the extraordinary 

 changes which these bodies suffer, and indeed a knowledge of 

 such matters is quite necessary in studying the histology of 

 either normal or diseased tissues. 



Unfortunately we are not always able to use human blood 

 for these demonstrations because the corpuscles are too small, 

 and consequently the alterations do not admit of easy observa- 

 tion. We naturally turn to an object that has larger corpuscles 

 and may be procured with little trouble or expense. 



The frog is therefore selected, or, even better still, the newt, 

 which is especially well suited for this purpose. At first the 

 blood may be examined in a menstruum similar to the liquor 

 sanguinis or plasma, and the frog's aqueous humor is usually 

 found satisfactory. 



To a drop of this latter add an equal quantity of the blood, 

 mix them well with a glass rod, and adjust an ordinary 

 | inch circle. The aqueous humor exerts no special influ- 

 ence over the corpuscles, and is therefore called an indif- 

 ferent fluid. If it be impossible to obtain aqueous humor, an 

 excellent substitute may be found in the fresh fluid from a 

 hydrocele or ovarian cyst, or we may use serum to which iodine 

 has been added, which is then called iodized serum. To six 

 ounces of the fluid twenty grains of finely powdered iodine are 

 added. After prolonged agitation the iodine will be dissolved, 

 and the mixture thus prepared may be kept for a number of 

 months. Suspended in this liquid the blood is studied to 

 advantage with a lens of moderate power, such as an ordinary 



