Localized Lesions Produced by Buried Radium. 383 



was only 1 mm. wide, and the maximum area of destruction (1 cm. 

 in diameter) was reached at about the end of two weeks. The 

 radium emanation loses its activity at the rate of 16 per cent, per 

 day, and in clinical usage the tubes, when used as in this method, 

 are said to have an effective period of irradiation equal to 132 

 hours. 



In our experiments similar slow-growing, localized lesions were 

 experimentally produced in the corpora striata of normal adult 

 dogs. It was our aim to produce such lesions and to study the 

 general physiological, and especially the neurological reactions 

 that might occur as a result of such destruction. Although we 

 were unable to produce at will the well-known clinical symptoms 

 associated with lesions of the lenticular or caudate nuclei, our 

 results are of interest in showing that an extensive amount of de- 

 struction of the basal ganglia is compatible with apparently normal 

 neurological reaction, and that the organization of the brain is 

 associated with marked compensatory ability. 



Well-grown dogs were used as subjects. Morphine and novo- 

 cain were used for anesthesia. The radium emanation tubes were 

 from 2.5 to 3.5 mm. in length, about 0.4 mm. in diameter and with 

 walls about 0.1 mm. thick. Each tube contained on the average 

 one millicurie of radium emanation. 



After anesthesia, a small incision was made in the scalp of the 

 treated animal, about one centimeter lateral to the median line 

 of the head, and just above the region of the coronal suture. A 

 2 mm. hole was drilled in the skull at about the intersection of the 

 superior temporal line with the coronal suture. Through this 

 hole the radium tube was inserted to the proper depth by means 

 of a long, fine steel trocar, 0.8 mm. in outside diameter. The tube 

 was left permanently in place. 



Fifteen dogs were treated. In six, unilateral destruction of 

 portions of the corpus striatum was performed, and the animals 

 were killed at varying periods, the maximum being about 8 months 

 after the operation. Four dogs were treated similarly, but at the 

 end of 2, 3 and 4 weeks respectively a similar lesion was produced 

 on the opposite side of the brain. In five animals a simultaneous 

 bilateral destruction was made of portions of the corpus striatum 

 on each side of the brain. 



