CORNEA-UMBILICAL CORD. 125 



This is the condition which we everywhere find recur- 

 ring in these tissues, and upon it will at the same time 

 be found to depend, as I hope you will convince your- 

 selves by direct observation, the size of the districts 

 invaded by disease ; every disease which essentially 

 depends upon a disturbance in the internal disposition of 

 the tissues is- always made up of the sum of the separate 

 changes occurring in such territories. But at the same 

 time the pictures which are here offered to us afford a 

 really aesthetical enjoyment through the delicacy of this 

 arrangement, and I cannot deny that, as often as I look 

 at a section of tendon, it is with a peculiar feeling of 

 satisfaction that I contemplate these reticular arrange- 

 ments, which effect a union between the exterior and 

 the interior, and, excepting in bone, can in no structure 

 be demonstrated with greater distinctness and clearness 

 than in tendons. 



Considering the structure of the cornea and the dispo- 

 sition of its parts, it would be most convenient, gentle- 

 men, to proceed at once to the consideration of its his- 

 tory, still I prefer reverting to it hereafter, inasmuch as 

 it is at the same time the most suitable object for the 

 demonstration of pathological changes. I will therefore 

 only observe here, that in the same way that tendons 

 have their peripheral system of vessels, and that their 

 internal parts are nourished by a delicate juice-convey- 

 ing system of tubes, so also in the cornea only the most 

 minute vessels extend a few lines over its border, so that 

 the central parts are completely destitute of vessels, as 

 indeed they were obliged to be, in order to allow of the 

 transparency of the tissue. 



I should like, on the other hand, in connection with 

 the foregoing tissues, to speak of one which has gene- 

 rally met with but little special preference in histology, 

 but is perhaps more likely to have some interest in your 



