226 BIOLOGY. [Book ii. 



and morphological composition -with the blood, in which it ends 

 by throwing itself. Eed globules are lacking thereto; but it 

 is probable that these are formed in the sanguineous vascular 

 system at the expense of the white globules of the lymph, and 

 of those which are generated in diverse closed glands, and of a 

 general texture analogous to that of the ganglions. We allude 

 to the glands called sanguineous, to the spleen, to the thyroid 

 gland, and so on. 



The metamorphosis of the white lymphatic globules into red 

 sanguineous globules is almost directly established by the fol- 

 lowing fact : — 



Burdach, having placed on a watch-glass some drops of the 

 blood of a dog, plunged the whole in a vessel filled with oxygen, 

 which he closed hermetically. He says that at the end of 

 twenty-four hours there was coagulation, and a red clot floated 

 in the serum. Burdach further says that through the help of 

 the microscope he saw in this clot globules, yellowish, ovalar, 

 biconvex, smaller than the sanguineous globules.^ 



On the whole, the lymphatic system is an auxiliary of the 

 venous system, with which, moreover, it largely communicates 

 in the inferior vertebrates. But its function is not simply to 

 convey to the heart and to the respiratory organs blood 

 vitiated by the activity of nutrition ; it furthermore undertakes 

 the duty of making up for the imperfections of the sanguineous 

 circulatory system by gathering a part of the plasma not 

 utilised, and finally, at the expense of this plasma, and of the 

 assimilable liquids obtained in the intestine, it fabricates white 

 globules. 



The movement of the lymph in the lymphatic vessels is so 

 curious as to deserve remark. Of the causes of propulsion which ■ 

 we have indicated in the sanguineous circulation, one, the car- 

 diacal contraction, is here absent. Nevertheless the lymph 

 marches, and even with a notable swiftness, since it bursts out 

 when we prick the thoracic canal below a ligature. Now its 

 ' Burdacli, Traite de Physiologie, t. II., p. 541. 



