246 DR. G. THIN. 



fluid were pencilled and then stained in carmine, picro- 

 carminate, logwood, and purpurine. Preparations previously 

 injected with Berlin blue were placed in Miiller's fluid and 

 picrocartninate. 



Before explaining what T observed in preparations thus 

 variously treated, it will be convenient to return to M. 

 Ranvier's paper. INI. Ranvier describes in the omentum a 

 network of cells which are destined to form new capillary 

 vessels. He therefore designates them " vaso-formative 

 cells," and especially insists that they are distinct from 

 the cells of the connective tissue ; the cell being, in fact, 

 sui generis. Examined in peritoneal serosity these cells are 

 described as " irregularly branched, finely granular, and 

 highly refractive. Their size, and the number and arrange- 

 ment of their prolongations are very variable. The branches 

 often anastomose with each other to form a network. In a 

 given milky patch into which the blood has not yet pene- 

 truted this network has the form of a capillary network." 

 He has not been able to determine the number of cells in a 

 network, but believes that it is not considerable, and that 

 one cell may form a whole network. 



In preparations which have been treated by Miiller's fluid, 

 pencilled and stained in carmine, Ranvier recognised that in 

 the midst of the granular protoplasm which forms the mass 

 of all the branches of the vaso-formative network, elongated 

 cylindrical nuclei are situated, whose long axis corresponds 

 to that of the branch which they occupy. These nuclei are 

 highly refractive and stain deeply with carmine. 



The questions which I endeavoured to answer from a 

 study of my preparations were : Does the appearance de- 

 scribed and figured by Ranvier constitute a definite structure 

 to which the term " cell " is applicable? and what relation 

 does it have to the formation of new blood-vessels ? 



In specimens stained in carmine and picrocarminate it is 

 possible to obtain preparations which correspond exactly to 

 Ranvier's figures of the " cellule vasQ-formative,^' but in my 

 experience appearances accurately corresponding to the 

 figure are rather the exception than the rule. Various 

 modifications of the appearance having, however, obviously 

 the same relation to a structural peculiarity of the tissue 

 are always found. Let us analyse the " cellule vaso- 

 formative " as described by Ranvier in stained preparations. 

 There is in an almost colourless ground substance a branched 

 pale red figure, and at difiierent parts of the figure more 

 deeply stained nuclei. There is nothing in this appearance 

 itself that would indicate that the figure represents a cell. 



