94 THE CELL DOCTRINE. 



is insoluble in acetic acid. The normal blood glob- 

 ules are not a transformation of the embryonic. 

 They appear by genesis in the midst of the blastema 

 of the blood. After the fourth month, the embry- 

 onic globules cease to form, and as the mass of the 

 blood increases, the proportionate number diminishes 

 with great rapidity. 



Leucocytes, or white blood globules, are found in 

 many tissues, in the blood, on the surface of mucous 

 membranes; in a word, they are the pus corpuscles. In 

 form, they are round, with pale, well-defined borders, 

 and contain extremely fine gray granules. They 

 possess a very thin envelope, and a granular cell 

 contents. The normal diameter is .008 millimetre 

 (Wutf f an inch). On the addition of water, the 

 leucocytes swell, the granular particles are agitated 

 by a peculiar movement (first observed by Brown), 

 and finally, a considerable number of these particles 

 unite, so as to form two or three little masses, that have 

 been mistaken for nuclei. Upon the addition of acetic 

 acid the same reaction follows, but with greater 

 rapidity. 



The mode of production may be followed, step by 

 step, upon the surface of wounds, especially little 

 ones. At first a hyaline liquid appears. At the end 

 of a couple of hours, this liquid becomes finely 

 granular, and then all at once, in the midst of the 

 granulations, we perceive small granular bodies an- 

 alogous to leucocytes, offering the same chemical re- 

 actions, but measuring only .003 millimetre (.000118 

 of an inch) in diameter. They are, in fact, leuco- 

 cytes of young growth. When leucocytes are re- 



