144 THE DISEASES AND DISORDERS OF THE OX. 



remote ancestral condition when the primary importance of cells 

 as units, distinct and not combined, was very much greater than 

 it can be in higher organisms in which each constituent cell is 

 most intimately dependent upon the activities of the other cellu- 

 lar units with which it is so intimately co-ordinated. Among the 

 different kinds of new formations the enchondromata most 

 pointedly illustrate the reversional characters of which we are 

 speaking. 



Enchondroma myxomatodes exhibits characters like those of 

 the notochord found in all vertebrata, and also in some in- 

 vertebrata. The cells, moreover, of some enchondromata 

 are stellate, their processes uniting to form a network, and 

 in the Selachii, the root-forms of the vertebrata, similar cells 

 are present. Again, these enchondromata are most usually 

 found in the limbs, and especially in the distal parts of the 

 limbs. Now the primary condition of the vertebrate limb is 

 seen in the Selachii, among which animals the limb is composed 

 of a great number of cartilaginous rods, which are arranged 

 definitely, and increase in number towards the distal extremity 

 of the pro-pterygium, the meso-pterygium, and the meta-ptery- 

 gium. It certainly appears possible that the enchondromata 

 situated in homologous parts may, so to say, point backwards 

 to the ancestral condition of the limb. Corroboration of this 

 statement is seen in the frequency with which cartilaginous 

 bodies develop in connection with certain joints of the limbs in 

 man and animals. These cartilaginous nodules may be either 

 single or multiple, and some may be as large as a small apple. 

 Cruveilhier figures several round cartilaginous bodies as occurring 

 in an elbow-joint, and it has also been observed that cartilage 

 cells have been found in the synovial tufts of some joints. 

 Similarly, Mr. T. Smith removed over 250 loose rounded carti- 

 lages from the knee-joint of a man on December 13th, 1882, at 

 St. Bartholomew's Hospital. He also operated on a woman 

 whose case has been recorded by Mr. Harrison Cripps, in The 

 Transactions of the Pathological Society of London, vol. xxvi. 

 This woman, aged twenty-eight, had for six years, in the upper 

 third of the right arm, immediately beneath the skin, a pyriform 

 tumour which was 3^ inches long, and 2 inches in diameter at 

 its thickest part, and tapered towards the axilla. Within its 

 capsule were found one large mass of cartilage, and twelve or 



