426 Mr. Lawson Tait on the 



tigation than I have yet been able to give to it. Virchow regards this 

 tissue as ranking with embryonic subcutaneous tissue and the vitreous 

 humour. I am not yet in a position to give an opinion on this relation- 

 ship, though I think it possible. 



This alveolated tissue is divided, throughout the whole length of the 

 cord, into three columns, one of which surrounds each blood-vessel. The 

 divisions between these three columns are not visible to the naked eye, 

 but they become very perceptible when the tissue is injected in the 

 manner to be immediately described. When the nozzle of the injecting- 

 apparatus is inserted into the tissue of one column, the fluid will be found 

 to travel along that district only, unless such pressure is used as produces 

 rupture of the limitation of the column. The injection will be found to 

 surround the blood-vessel of its district with great uniformity (as shown 

 in Plate 11. fig. 4), but the injection will never be found to encroach upon 

 the walls of the vessel. The limitation can scarcely be said to be mem- 

 branous ; for if the adjacent tissue of two columns be injected, the line 

 of demarcation where they touch cannot be made out. It seems to 

 depend upon the absence of communication between the canals of the 

 two columns. This is a most interesting fact bearing on the nutrition 

 of the blood-vessels. 



Virchow describes the proper substance of the cord as consisting of 

 "reticulated tissue, the meshes of which contain mucin and a few 

 roundish cells, whilst its trabecule are composed of a striated fibrous 

 substance in which lie stellate corpuscles. When a good preparation has 

 been obtained by treatment with acetic acid, a symmetrical network of 

 cells is brought to view, which splits up the mass into regular divisions." 



Kolliker considers the substance to be "immature connective tissue 

 with stellate anastomosing cells." Weisemann thinks " it corresponds to 

 the skin and subcutaneous tissue in arrest of development." But it 

 seems to me, however probable their explanations of the biological 

 relations of the tissue may be, that their descriptions of its anatomy 

 are only partially accurate and far from being complete. The facts are 

 that the striated fibrous tissue is composed of the collapsed walls of 

 numerous canals of which alone the proper tissue of the cord is made 

 up. When only partially emptied some of them appear like stellate 

 cells, and therefore they give the deceptive appearance of there being a 

 matrix in which Virchow's " connective-tissue corpuscles" are imbedded. 

 In the lacunar spaces of the system oval nuclei are imbedded in the 

 walls of the canals. In a large number of observations I have never 

 seen these nuclei alter their shape and position. 



Before detailing the results of my observations on these canals, it will 

 prove more satisfactory if I describe my methods of preparing the speci- 

 mens observed. First of all I may say that I have in no instance drawn 

 a conclusion from observations made on a cord otherwise than perfectly 

 fresh, unless it is distinctly stated to the contrary. I have found the 



