BLOOD-VESSELS OF THE SEROUS MEMBRANES. 61 



The principle according to which the formation of capillaries takes 

 place is similar to that which was first pointed out by Strieker in the 

 new formation of blood-vessels in the tadpole and in inflammation, 

 and which was afterwards confirmed in every detail by Arnold. But 

 we must here remark that in our lymphangial nodules, patches, and 

 cords, the new formation of blood-capillaries does not take place by 

 the sending forth of protoplasmic buds from the wall of a capillary, 

 which are then excavated, starting from the vessel ; but this excava- 

 tion goes on both from the already formed vessel, and also isolated 

 in the branched lymph-canalicular cells, which are in direct con- 

 tinuity with the endothelium of the blood-vessels. 



Precisely the same mode of development may be shown in the 

 previously-mentioned gelatinous body of the infra-orbital fossa. Here 

 a number of places may be found in the neighbourhood of the fat- 

 body where there is as yet no formation of fat in the groups of 

 branched cells, and where, nevertheless, an active development of 

 capillaries is going on. From place to place we find such accumula- 

 tions of branched cells and young capillaries, in which, on the one 

 hand, the direct connection of the former with the wall of the latter 

 may be easily seen, and, on the other hand, the excavation of already 

 formed capillaries into those cells as well as the isolated vacuolation 

 of the branched cells may be followed through all stages, It seems, 

 from what has been said of this hyaline body, and of the development 

 of fat-tissue in the omentum and the mesentery, to be the general 

 rule, that the transformation of the branched cells of those cords and 

 nodules into fat cells is preceded by the development of a correspond- 

 ing system of capillary blood-vessels. 



