122 THE BLOOD. 



stance of which are embedded a greater or less number of 

 minute granules. These have been called by Robin, Leucocytes. 

 This name seems more appropriate, than that of white or 

 colorless blood-corpuscles, inasmuch as they are not peculiar 

 to the blood, but are found in the lymph, chyle, pus, and 

 various other fluids, in which they were formerly known by 

 different names. All who have been in the habit of exam- 

 ining the animal fluids microscopically, must have noticed 

 the great similarity existing between the corpuscular ele- 

 ments found in the above-mentioned situations. As mi- 

 croscopes have been improved, and as investigations have 

 become more exact, the varieties of corpuscles have been 

 narrowed down. !Now it is pretty generally acknowledged 

 that the corpuscles found in mucus and pus are identical ; 

 also that there is no difference between the white corpuscles 

 found in the lymph, chyle, and blood ; and finally, the recent 

 investigations of Eobin have shown that all of these bodies, 

 which were formerly supposed to present marked distinctive 

 characters, belong to the same class, presenting but slight 

 differences in different situations. The description which 

 will be given of the white corpuscles of the blood, and the 

 effects of reagents upon them, will answer, in the main, for 

 all that are grouped under the name of Leucocytes. 1 



Leucocytes are normally found in the Blood, Lymph, 

 Chyle, Semen, Colostrum, and Yitreous Humor. Patholog- 

 ically they are found in the secretion of mucous membranes, 

 after the slightest irritation, and in inflammatory products, 

 when they are called pus corpuscles. 



In examining a specimen of blood with the microscope, 

 we immediately notice the marked difference between the 

 leucocytes and red corpuscles. The former are globular, 

 with a smooth surface, but rendered somewhat opaque by 



* For a full account of the Anatomy and Physiology of these bodies, the reader 

 is referred to an elaborate article on this subject by Robin in the Journal de la 

 Physiologic, tome ii., p. 41, and the article "Leucocyte" in Nysten's Dictionary, 

 Paris, 1858. 



