PHYSIOLOGY AND EXPERIMENTAL PATHOLOGY 375 



period." During this time, however, the tissues seemed to be less firm 

 and the bones somewhat less rigid in the experimental than in the con- 

 trol dogs. Then followed a "period of adiposity." The dogs ate raven- 

 ously and became fat. Their intelligence diminished and they became 

 "dreamy and melancholy." This period lasted two or three months. 

 Then followed a stage of cachexia with "thymic idiocy." During this 

 period the dogs were subject to spontaneous fractures and were very liable 

 to different infections. The hair became dry and fell out. The dogs 

 became weak and ultimately died in coma. When the operation was de- 

 layed until the third or fourth week the various periods were prolonged. 

 If the thymus was removed as late as the fifth or sixth week, merely tran- 

 sitory symptoms or none at all appeared. In well-developed cases, inter- 

 ference with bone metabolism was marked. The long bones were shorter 

 than normal and microscopically they showed a picture amounting to 

 osteoporosis. Correspondingly the calcium content of the bones was re- 

 duced. Experimental fractures were slower in healing in the thymecto- 

 mized than in the control dogs. 



In explanation of their findings, Klose and Vogt evolved a theory that 

 in early life the thymus functions as an organ of "nuclein synthesis." 

 In the absence of the thymus phosphoric acid, or possibly nucleic acid, 

 fails of neutralization and gives rise to acidosis with consequent decalcifica- 

 tion of the bones and degenerative conditions in nervous and other 

 tissues. 



Matti, in 1913, reviewed the work on thymus function up to that 

 date and reported numerous original observations on thymectomy. His 

 series included 36 puppies and 4 rabbits. All of the rabbits and 6 of the 

 puppies died shortly after the operation. He operated upon the dogs 

 from the eighteenth day to the twelfth week of age. In contrast with 

 Klose and Vogt, he obtained most striking results when the subjects were 

 more than 5 weeks old. The animals were observed from 2 to 10 months. 

 The greater proportion of Matti's experimental series gave negative re- 

 sults. He was content to dismiss these from consideration, however, on 

 the ground that there were probably bits of thymus inadvertently left be- 

 hind to carry on the functions normally pertaining to the gland. No proof 

 was afforded that such was the case. A few of the dogs developed some- 

 what striking symptoms. They became weaker and more sluggish than 

 the control animals ; the bones became soft and bent under the body weight ; 

 finally, the animals became so weak that they were unable to support them- 

 selves. The bone changes can be succinctly described as rachitic. Vari- 

 ous changes in the different endocrin "organs were also observed and on 

 these Matti laid considerable stress. 



During the past decade a considerable number of researches upon 

 thymectomy have been published by different observers. Some obtained 

 negative results and others obtained in varying degree suck results as 



