THE BLOOD. 55 



observers in reference to the nature of the white corpuscles, 

 we will next pass to the consideration of their origin or 

 mode of formation. The idea that the white corpuscles are 

 elaborated by the lymphatic glands has already been referred 

 to ; and, from the absence of these glands in the lower ovipa- 

 rous vertebrata, it is evident that they cannot be regarded as 

 essential to their formation. 



It has been stated that, in addition to the white and red 

 globules, numerous smaller particles, termed molecules, exist 

 in the blood. The white globules, in all probability, derive 

 their origin from these molecules, a number of them going 

 to constitute a single white globule. This aggregation of 

 the molecules into masses, or globules, would appear to result 

 from the operation of a general law of the economy, under 

 the influence of which the globules unite with each other, 

 and become invested with a coating, or membrane, probably 

 of an albuminous nature. 



Donne believes also that he has traced, by direct observa- 

 tion and experiment, the transformation of the minute oily 

 and fatty particles, found in the milk, into white globules. 

 He injected numerous animals, birds, reptiles, and mamma- 

 lia, with various proportions of milk, and, strange to say, the 

 creatures thus experimented upon experienced no injurious 

 effect beyond a momentary shock, with, however, the single 

 exception of the horse, to which the experiment proved fatal 

 in seven different cases. If, almost immediately after the 

 injection of the milk, a drop of blood be withdrawn from the 

 system at a distance from the point where the milk was intro- 

 duced, a number of the globules of the milk may be detected 

 quite unaltered, and which may be recognised by their ge- 

 neral appearance, their smaller size, and, lastly, by the action 

 of acetic acid, which dissolves the red globules, renders ap- 

 parent the granular texture of the white, but leaves untouched 

 the molecules of the milk. If the blood be again examined 

 at about the expiration of two hours, the smallest milk glo- 

 bules will be seen to have united themselves with each other 

 by threes and fours, and to have become enveloped, by 

 circulating in the blood, in an albuminous layer, which forms 



F 



