MEMOIRS. 



On the Formation 0/ Blood-vessels, as observed in the 

 Omentum of Young Rabbits. By G. Thin, M.D. 

 (With Plate XV, figs. 1—5.) 



When new capillary blood-vessels are formed from pre- 

 viously existing vessels in a tissue sufficiently transparent to 

 be examined under the microscope, there is an appearance 

 constantly observed, regarding the cause of which there 

 is much difference of opinion. From the wall of the capillary 

 a conical mass projects into the surrounding non-vascular 

 tissue, and it is frequently continued into a similar mass that 

 meets it from a neighbouring or from another part of the 

 same vessel. Nuclei are visible at various parts of the tract 

 thus indicated, and later a fully formed capillary is found to 

 have been formed in it. 



Golobew' believes that the first stage in this projecting 

 jnass is an outgrowth from a spindle-cell in the wall of the 

 vessel, and that the new formation extends by a hollowing 

 out of the process and a multiplication of spindle-cells, which 

 bend over towards each other. The dark lines seen in a 

 capillary treated by silver correspond to the line of junction 

 of the borders of two spindle-cells. 



Kolliker^ at one time taught that a " bud" (sprossen) grew 

 out from the wall, and either joined a similar bud from 

 another or the same vessel, or became continuous with the 

 spindle or stellate cells of the tissue. In the last edition of 

 his work he acknowledges that with the present better 

 knowledge of the structure of capillaries these views are no 

 longer tenable. 



Strieker considers that the projecting process proceeds from 

 a stellate cell in the wall of the capillary, which aiiastomoses 

 with other stellate cells in the tissue. The widening of the 

 lumen of these processes constitutes the new vessel. This, of 



' ' Arch. f. Mic. Anat.,' 1869, p. 49. 

 ' 'Handbuch der Gewebelehre.' 



VOL. XVI NEW 8ER. Q 



