CHAPTER XXI. 

 THE NERVES. 



THE nervous system began to be investigated colloid-chemically 

 when the problem of brain swelling and edema of the brain was 

 formulated through FISCHER'S theory of edema (see p. 223). Various 

 attempts were made to determine whether the swelling induced by 

 acids and in the presence of salts was analogous to the swelling of 

 fibrin. From the start it was not very probable that nervous tissue 

 was like the latter, an individual protein substance. Though the 

 nerve cell consists mainly of protein material, the neurolemma which 

 serves as insulation for nerve conduction is largely formed from 

 lipoids which behave quite differently towards acids and salts. 



MARTIN H. FISCHER and M. 0. HOOKER conducted experiments 

 upon the swelling of brain and cord in acids and salt solutions and 

 discovered that their behavior quite paralleled the behavior of fibrin. 1 



For reliable data it is important to employ absolutely fresh nervous 

 tissue from normal animals; results of no comparative value were 

 obtained from diseased rabbits or animals which had been chased 

 about before they were killed. FISCHER justly criticizes the experi- 

 ments of J. BAUER and of J. BAUER and AMES who used material 6 

 to 24 hours post mortem; the post mortem accumulation of acids 

 rendered these experiments useless for the purpose of comparison. 



The experimental attempts of BARBIERI and CARBONE to produce 

 swelling by injection of acids into living animals we must regard as 

 naive. The authors evidently overlook the fact that the acids are dis- 

 tributed in the organisms and that various organs compete for the avail- 

 able water; we may expect swelling only from local accumulation of 

 acid. On this account the interesting experiments of KLOSE and VOGT 

 deserve elaboration in the direction of colloid research. The authors 

 found in thymectomized dogs an acid preponderance localized among 

 other places in the nervous system (gray matter) ; the brain of a thy- 

 mectomized dog completely filled the skull, the ganglion cells were 

 swollen. R. E. LIESEGANG justly cautions anthropologists against 

 attributing too great significance to the weight of brains (PETTEN- 



1 This parallelism must not be applied too generally; there are important 

 differences in behavior with the salts of the heavy metals as hitherto unpublished 

 experiments of H. BECHHOLD show. 



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