S06 M. Treviranus on the Organic Structure 



tissues of the body, from which, again, the lymphatics return 

 the colourless blood ; in fact, they are the veins of the white 

 tissues. In most parts, and this refers to the cellular membrane 

 generally throughout the body, the blood, after being used, and 

 before it can be allowed to join the general circulation with 

 safety, requires to be elaborated in glands in which a gradual 

 change in the white blood is effected, and a gradual reunion 

 with the red blood is promoted. In some few organs, as the 

 brain and the ball of the eye, no lymphatics have been disco- 

 vered. In these we may suppose, that some reason exists which 

 prevents the white blood, after being used, from being necessari- 

 ly injurious, and here, consequently, it is at once mixed with the 

 blood of the veins, and the minute transparent vessels which re- 

 ceive it in the first instance do not therefore undergo the changes 

 above mentioned, as preparatory to the formation of lymphatics. 

 On the contrary, they proceed at once to join the minute veins. 

 It is also very remarkable, that, in the organs in which no lym- 

 phatic glands are found, we have but one order of tissues, the 

 white. This is the case in the eye-ball and brain. 



Many reflections arise from the consideration of this fact ; but 

 I must return to our author, who has expended much labour 

 and research on the lymphatic terminations in the alimentary 

 canal, with respect to which, he has convinced himself that the 

 villous flocculi, so abundant on the mucous membrane, are com- 

 posed of minute tubes packed together, and continuous with 

 neighbouring lymphatics. He thinks that some of his observa- 

 tions render it very doubtful whether the old opinion, that 

 some of the lacteal terminations have open mouths, or rather 

 perforations in their extremities, may not after all be correct. 



But not only do we find lymphatic terminations in the villi of 

 the mucous membrane and in its general surface, but also in its 

 crypts and follicles, which Treviranus considers to be organs of 

 absorption as well as of secretion. To conclude, Treviranus 

 agrees with Miiller and others, that the ultimate terminations of 

 all the ducts of glands are, in the form of very minute tubes, 

 collected into lobules, and terminating each in a cul de sac ; the 

 whole mass is connected by cellular membrane, and in this way 

 is formed the parenchyma of every secreting organ. In some 



