178 MR. TOYNBEE ON THE ORGANIZATION AND NUTRITION 



More limited observations upon the state of these vessels in subsequent periods 

 of life, lead to the belief, that, compared to the size of the fib ro- cartilage, they gra- 

 dually become more scanty and small from the period of youth to that of old age. 



3. Researches upon the vessels of the Jihro-cartilage of the sym'physis pubis lead 

 me to conclusions similar to those I have just related. 



Of the Vessels of the Inter-articular Fihro-Cartilage. — ^The central part of the in- 

 ter-articular fibro-cartilages, in the injected specimens that I have examined from the 

 human foetus as early as the third or fourth month, does not contain any vessels. I 

 possess, however, the inter-articular cartilage of the temporo-maxillary articulation of 

 a foetal Calf, which is pervaded by blood-vessels throughout its entire substance ; a 

 disposition which may take place in all fibro-cartilages at very early periods of their 

 development. Subsequent to these very early periods, however, the central portion, 

 which, like articular cartilage, is subject to concussion and compression, does not 

 contain any blood-vessels. 



The inter-articular fibro-cartilages are pierced at their circumference by arteries 

 of considerable size, which converge towards the central cartilaginous portion, into 

 which, however, they do not penetrate, but upon its confines they form dilatations, 

 with which the veins are continuous*, Plate XV. fig. 7- 



In some instances, as in the sterno-clavicular fibro-cartilage, the arteries form intri- 

 cate ramifications and convolutions at the circumference of the cartilage ; in other 

 instances, as in the semilunar fibro-cartilages of the knee-joints, they terminate in 

 more simple dilatations, Plate XV. fig. 7- 



The vessels of the fibro-cartilages in some parts, as in those of the knee, form a 

 most intricate flexus in the fibrous tissue. 



Vessels extend to a short distance on the surface of fibro-cartilages, beneath the 

 synovial membrane, but they are arrested at the part where these structures are sub- 

 ject to pressure, and at this margin they form dilatations similar to the synovial 

 vessels which cover the border of articular cartilages. 



The Second Class of Non-vascular Animal Tissues. 



Of the Cornea, the Crystalline Lens, and the Vitreous Humour. 



The organs enumerated above may be considered as constituting a class of non- 

 vascular organized tissues, inasmuch as each of them is transparent, each forms 

 a part of the eye-ball, and performs a similar function, viz. of transmitting the 

 rays of light to the retina. These three structures are nourished by the penetration 

 into them of a nutrient fluid, which is derived from the numerous blood-vessels 

 which encircle them ; although each of them contains corpuscles, they differ from 

 each other in their structure as well as in their relations with the vascular system. 

 Thus the crystalline lens is soft externally, and hard towards its centre, and the 

 * For the injection of the blood-vessels of fibro-cartilage, young subjects should be selected. 



