DEPENDENCE OF TISSUES UPON THE VESSELS. 



and non-vascular parts ; and that, if the nutrition of 

 individual parts is considered to be directly dependent 

 upon the vessels or the blood, it must at all events be 

 demonstrated that all the elements which stand in im- 

 mediate connection with one and the same vessel, and 

 are assigned to a single vessel for their support, present 

 conditions of life essentially similar. In the case of bone 

 it would be necessary to show that every system of 

 lamellae which has only one vessel for its nutrition, 

 always exhibits a similar state of nutrition. For if that 

 vessel, or the blood which circulates in it, be the active 

 agent concerned in the nutrition, the utmost that can be 

 admitted is, that one part of the elements may be more, 

 another less, subjected to their influence ; but still it 

 must essentially be a common and similar influence 

 which they experience. That this is no unreasonable 

 requirement, that a certain dependency of definite terri- 

 tories of tissue upon definite vessels must undoubtedly 

 be admitted, the most beautiful illustrations are afforded 

 us in the doctrine of metastases, in the study of the 

 changes which are effected by the occlusion of single 

 capillary vessels, and with which we have become ac- 

 quainted from the history of capillary embolia. In such 

 cases, in fact, we see that a whole portion of tissue, as- 

 far as its immediate connection with a vessel extends, i 

 its pathological relations also constitutes a whole a vas- 

 cular unity. But this vascular unity to a finer appre- 

 hension still appears a compound, and it is not sufficient 

 to split up the body into vessel-territories (Gef assterri- 

 torien) alone, but within them a farther division must be 

 made into cell-territories (Zellenterritorien). 



This view has, I think, been essentially furthered by 

 our having discovered, as I lately pointed- out to you (p. 

 76), the existence of a special system of anastomosing ele- 

 ments in the connective-tissues, and by our having ir; 



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