ORGAN AND BODY SYSTEMS 509 



reaction. The majority of the painful skin lesions reported are of the 

 chronic, degenerative type. In areas of severely damaged skin where the 

 production of severe pain is of such great chronicity as that described in 

 radiologists and patients having roentgen ulcers, the mechanism is 

 probably one of scarring and contracture of connective-tissue around 

 nerve endings and thus related to damage of the connective-tissue cells 

 rather than direct damage to the nerve trunk or nerve endings themselves 

 (78). 



It should be pointed out that the symptoms resulting from changes 

 brought about in the central nervous system by irradiation will vary in 

 accordance with the location of the lesions produced. While it is reason- 

 able to expect that there will be certain variations in sensitivity of the 

 various cell types which go to make up the brain and cord and ganglia, 

 the symptomatology may be generalized rather than specific. The 

 skull diminishes appreciably the effective dosage delivered to the brain 

 substance. It should be possible to bring about disturbances in the 

 spinal fluid mechanism through chronic damage of the blood vessels of 

 the choroid plexus wherein changes might be produced, such as those 

 brought about in capillaries elsewhere (kidney, skin, heart, etc.). It is 

 likely that further studies, patterned after the experiments of Lyman 

 et al (206), though complicated in execution, would yield considerable 

 information concerning minor changes in brain cells which may be of 

 transitory or of permanent character. Conditioned animals should be 

 used for such experiments. Reports of changes in the vegetative nervous 

 system are in the reviewer's opinion as yet controversial. This field is 

 open to research but should be investigated only by those well trained in 

 studying this system from other points of view. 



BONE AND CARTILAGE 



Bone and cartilage (see also section on Teeth) are resistant to 

 roentgen radiation. It is common therapeutic knowledge, however, 

 that cartilage may be damaged by very intensive irradiation for car- 

 cinoma, especially in the neck region where the structures of the larynx 

 and trachea may be severely damaged and the cartilage may slough 

 whenever intensive cross-fire dosage is used (cf. 95, 397). 



Phemister (269) inserted a 12.5-mg. needle of radium into the lateral 

 surface of the condyle region of the femur of the dog for 18 hr. There 

 was necrosis of the bone and cartilage with disintegration of the marrow. 

 White fibrous connective tissue with very few cells, filled the marrow 

 spaces; cartilage was partially replaced by fibrocartilage. Instead of the 

 formation of a sequestrum, there was a very slow creeping replacement of 

 the necrotic bone by new bone, unless infected. There was considerable 

 destruction of the surrounding soft tissue which contributed to the delay 

 in heahng. Placing 37.5 mg. near the shaft of the femur for 20 hr. 



