241 



future time, of a theory which shall not be altogether un- 

 satisfactory. 



8. Among the many real difficulties which impede our un- 

 derstanding of the relations of the absorbent system, physiologists 

 have perplexed themselves chiefly about one, and that one of no 

 great importance. How, it is asked, do these vessels propel their 

 contents? It may be said, briefly, either by capillary attraction or 

 by an operation dependent upon properties of life. With respect 

 to the first, it cannot be asserted that it obtains in no instance, 

 though it appears probable that the laws of matter are in this 

 case, as iu most other animal processes, superseded by the laws of 

 life. There are no proofs of absorption by absorbent vessels after 

 death: cysts, before turgid, may collapse; swellings containing 

 fluids may appear to subside; but these changes may be attributed 

 in part to the difference of position in which such swellings are 

 examined before and after death, and in part to that general 

 flaccidity which ensues from the want of distention by the circula- 

 tion of the blood. Without entering into a full discussion of 

 lesser circumstances, it is sufficient to remark the most important 

 fact which has relation to this subject, viz. that lacteal absorption 

 has never been observed to proceed after death, although the lac- 

 teal system of animals have been examined at times when the 

 intestines have abounded with chyle. If absorption were capillary 

 or mechanical, as fluids exist in the intestines after death up to 

 the period of their decomposition, so an unremitting absorption 

 up to this period should take place; and lacteal fluid should in- 

 variably be found mixed with the blood of the right side of the 

 heart and its contiguous veins. As such is not the fact, we are 

 compelled to acknowledge the dependence also of this process of 

 absorption, upon the agency of properties of life. 



9. With respect to the manner in which an absorbent propels 

 its contents, other theories have been proposed ; they are none of 

 them worth consideration : and, to add to their number another of 

 about the same value, it may be suggested that the contents of an 

 absorbent are propelled by a vig a tergo, and that the origin of 

 this force is not in the heart, as in the case of the circulation of the 

 blood, but in the absorbent orifices; that is, fluids, &c. are in. 

 cessantly drawn into the mouths of the absorbent vessels by the 

 affinity which the life of these spheres has with certain particles: 

 that the vital properties perform this function in connection with 

 their assimilation, and hence these properties have relation with 

 successive quantities of the fluids they affect; which process at the 

 absorbent orifices being unremitting, gives rise to a circulation in 

 the tubes by a vis a tergo. 



10. A process which has been mentioned in the article on 

 Growth may be here again adverted to. If a portion of nerve is 

 removed, the intervening substance by which the interspace is 

 filled up gives place to the progressive growth of the nerve. It 

 may here be said merely, that absorption is subservient, under cer- 

 tain circumstances, to the laws of growth. 

 K K 



