72 BIOLOGY. [BOOK i. 



Sometimes the leucocytes are in considerable number in the 

 blood, to which they communicate a greyish tint or the tint of 

 wine lees. Their number in such cases attains and even sur- 

 passes the infantine and embryonary proportion. It is important 

 to remark that in such instances of leucocythcemia, there is 

 generally a swelling either of the liver, or of the spleen, or of 

 the lymphatic glands. 



The leucocytes are not met with merely in the blood : they are 

 also found in the living plasma, which we have yet to study, in 

 the lymph, and then it is observable that they are more 

 numerous in that liquid when it is examined beneath the 

 lymphatic glands. 



Lastly the leucocytes float in variable numbers in most of the 

 humours of the economy. We can view them in relation to the 

 granulous corpuscles existing so numerously in pus. However, 

 in these last globules the amoeboidal movements are less evident, 

 and the nuclei not so easily seen. 



The leucocytes are met with in the blood of all the mammifers 

 and also in that of birds, of reptiles, and of fishes. However, 

 while the red globule is peculiar to the vertebrates, the white 

 globules, on the contrary, exist also in the invertebrates. 



"We have signalised the presence of the leucocytes in pus ; but 

 we also find them in the blastema of cicatrices, in what is called 

 the plastic lymph. 



We can only make conjectures more or less plausible on the 

 office of the white globules. Peradventure we may regard them 

 as a transitory, primitive, state of the red globules. 



We know in effect that the first embryonary globules, those 

 which we cannot help regarding as the first pattern of the red 

 globules, are nearly colourless, like the white globules, that like 

 them they have a nucleus, and lastly, that certain inferior verte- 

 brates have only colourless globules. The abundance of the 

 leucocytes in the blood of the mammiferous embryon comes also 

 as a confirmation of this hypothesis. If this manner of regard- 

 ing the subject had a solid foundation, then by bringing into 



