ITS MORPHOLOGICAL ELEMENTS. 283 



or the colourless blood-corpuscles, being distinguished from the 

 latter only in this, that they represent different stages of the 

 development of these cells. They present considerable variety 

 of size and form, exhibiting in some cases a distinct, and in others 

 an indistinct nucleus, and sometimes even a cleft nucleus which 

 frequently remains indistinct until it is treated with water, and 

 hence these corpuscles appear in the chyle itself like mere faintly 

 translucent vesicles. It is worthy of notice that many of these 

 bodies have frequently a magnitude of l-200th of a line in the 

 lacteals of moderate calibre, whilst the size of those in the chyle 

 of the thoracic duct seldom exceeds l-250th or l-350th of a line. 



We have already noticed their chemical relations in speaking 

 of the colourless blood- corpuscles, and we purpose again reverting 

 to the subject under the head of pus-corpuscles. 



If the search be conducted with care, coloured blood- corpuscles 

 may always be found in the chyle of the thoracic duct, although, 

 they are not present in large quantities. 



In order to obtain the largest possible quantity of fresh chyle, 

 the animal should be killed from two to five hours after feeding, 

 either by strangulation or pithing, the thoracic cavity opened, and 

 the thoracic duct tied immediately before its entrance into the 

 subclavian vein. After a short time the duct will be filled with 

 chyle, and will appear distended or as if it were injected. It must 

 then be carefully dissected into the abdominal cavity as far as the 

 receptaculum, and the contents discharged with care (in order to 

 avoid all admixture of blood), either by means of a fine trochar or 

 by simple incision. A greater quantity of chyle may be obtained 

 by laying open the thoracic portion of the duct and suffering the 

 chyle to flow from the incision ; but the precipitous flow of chyle 

 in the freshly killed animal may possibly give rise to a more 

 abundant flow of lymph and aqueous fluid, so that the chyle may 

 not possess a perfectly normal character. 



In reference to the chemical constituents of the .chyle, we may 

 observe that they entirely correspond with those of the blood ; 

 and hitherto only very slight, or even wholly unimportant dif- 

 ferences have been observed to exist between the plasma of the 

 blood and the chyle. This admits of a ready explanation, for 

 an accurate chemical analysis is only practicable in the case 

 of the chyle of the thoracic duct, which not only resembles the 

 blood far more closely than does the chyle of the smaller vessels, 

 but which has even taken up blood that is already coloured, to- 

 gether with blood-corpuscles, from the lymphatics of the spleen. 



