Journal of Applied Microscopy. 529 



NEUROLOGICAL LITERATURE. 



Edith M. Brace. 



Literature for Review should be sent to Edith M. Brace, Biological Laboratory, 

 University of Rochester, Rochester, N. Y. 



Thompson, Helen B. The Total Number of Data are added to those given by Karl 



Functional Nerve Cells in the Cerebral Hammarberg in his monograph " Stu- 

 Cortex of Man, and the Percentage of the ° o r 



Total Volume of the Cortex composed of dien iiber Klinik und Pathologic der 



Nerve Cell Bodies, Calculated from Karl Jdiotie nebst Untersuchungen iiber die 



Hammarberg s Data; together with a Com- ° 



parison of the Number of Giant Cells with normale Anatomie der Hirnrinde. 



the Number of Pyramidal Fibers Jour. Upsala, 1895." Basing her calculations 

 Comp. Neur. 9: 1 13-140, 2 rigs., 1899. ^ . ° 



upon these results, Miss Thompson esti- 

 mates that the total number of functional nerve cells in the adult human cerebral 

 cortex is 9,200 million that the proportion of functional nerve cells in the cortex 

 is 1.37 per cent, and that the number of giant cells in the cerebral cortex of man 

 is almost the same as the number of pyramidal fibers passing to the spinal cord. 



E. M. B. 



_ , , u u A T.T , o- i^ From data given by Hammarberg and 



Donaldson, n. n. A Note on the Significance a j o 



of the Small Volume of the Nerve Cell by Miss Thompson it is estimated 

 Bodies in the Cerebral Cortex of Man. Jour. ^j^^^ ^^^ weight of all the cell bodies in 

 Comp. Neur. 9: 141-149, 1899. ° 



the human encephalon is less than 27 g. 



and that the cells of the cortex with their dendrons weigh about 13 g. The 

 small volume of the cell bodies is a feature of the entire encephalon. 



Comparison of human encephala grouped according to race, sex, mental 

 power, stature, and age, show that differences in weight within each group are 

 always more than twice that of all the nerve cell bodies, and hence these 

 differences depend mainly upon variations in the medullary substance. 



■There is evidence that the dendrons of the cortical cells and their associated 

 terminals furnish the structural basis for intelligence, and that degrees in mental 

 power may be correlated with degrees in their complexity. The neurone may be 

 divided into three parts, the receiving portion, the conducting, and the transmit- 

 ting, corresponding to the cell body with its dendrons, the axone, and the ends 

 of the branches, or the terminals. Since the weight of the cells of the encephalon 

 is small, variations in the weight of the dendrons and terminals, which would be 

 correlated with increased mental development, would be correspondingly slight, 

 and though of the highest physiological importance, would not be detected by 

 the method of weighing or might be masked by the greater growth of the medul- 

 lary substance. e. m, b. 



The spinal nerves vary in architecture 

 Hardesty, Irving. The Number and Arrange- ,. ^ ^1 • •^- j ^u 



men. of the Fibers forming the Spinal Nerves accordmg tO their position, and the 

 of the Frog. (Rana virescens). Jour. Comp. same nerves show variations of gross 



Neur. 9: 64-112, pis. 6-17, 1899. . . j.rr i. • j- -j 1 



^ J' vv anatomy in different individuals. 



By counting the nerve fibrils at different levels it was found that the number 



of fibrils in the ventral roots decreases from the spinal cord toward the ganglion, 



