THE THYMUS GLAND 119 



that the changed conditions of ossification resulting from the 

 suppression of the thymus may be the forerunners of rickets. 



Basch endeavours to find an explanation of the changes 

 in the bones, in the metabolic conditions which obtain in 

 thymectomized animals. As C. Bracci pointed out (1905), the 

 removal of the thymus of rabbits causes a reduction of Ca in the 

 bones and other tissues. Basch investigated the amount of cal- 

 cium salts excreted in the urine; he found that, during a period 

 of eight days and under precisely similar conditions, the 

 thymectomized animals excreted more than twice the amount of 

 calcium excreted by control animals. This difference disappeared 

 some considerable time after extirpation. 



In contrast to this, however, Sinnhuber found that neither 

 the extirpation of the thymus nor the exhibition of thymus gland 

 was followed by an increased excretion of lime in the faeces or 

 the urine. Basch explains this discrepancy with his results by 

 a difference in the conditions under which the experiments were 

 performed, Sinnhuber's control animal being taken from a 

 different litter to that from which the thymectomized animal was 

 taken ; and, moreover, the control animal had previously suffered 

 from a serious nutritional disturbance characterized by exception- 

 ally high excretion of lime. 



Basch also describes a litter of puppies, a few weeks old, in 

 which the development of the bones was proportional to the 

 growth of the thymus, while there was no apparent modification of 

 the development of either the thyroid or the testicles. 



He also found that, where a portion of the thymus was left 

 in situ, there was less difference in the formation of the callus and 

 that, in some instances, it was quite normal. In one such case 

 he observed a hypertrophy of the remaining lobe of the thymus. 



U. Soli also found that thymectomy was followed in young 

 rabbits by changes in the development of the skeleton, these 

 changes affecting the hollow long bones and the ribs. 



Sommer and Floerken (1908) described the results of 

 thymectomy and transplantation of the thymus in both dogs and 

 cats. The thymus was removed from the animals at the age of 

 two months ; they lived for six to seven months, and differed from 

 the control animals of the same litter in awkwardness of shape, 

 clumsiness of movement, and roughness of coat. Skiagrams 

 showed that the long bones were much shorter and clumsier than 

 those of the control animals. In the case of animals in which 

 a thymus had been implanted, the long bones showed, on the 

 contrary, an increase in the processes of longitudinal growth. 



Ranzi and Tandler (1909) showed some dogs from which the 

 thymus had been removed by a median section of the sternum. 

 To prevent pneumothorax, this was done in Sauerbruch's 

 negative-pressure chamber. Three and a half months after 

 operation the animals weighed less than control animals from 



