CoGHiLL, Structure of the Nerve Cell. 195 



Van Durme (01) has studied with the Nissl method the Pur- 

 KiNjE cells and the cells of the cerebral cortex of the rabbit under 

 conditions of rest, fatigue and exhaustion. In the cerebellum of the 

 normal specimen at rest he finds cells of two types: "chromophiles," 

 with relatively large amount of chromatin ; and "chromophobes," with 

 relatively small amount of chromatin Both types vary greatly in size. 

 In the chromophiles the protoplasm is uniformly blue with sharply 

 colored chromatic bodies of various form and size. The larger ones 

 lie near the nucleus and a crescent of chromatic substance rests upon 

 the side of the nucleus. The nucleus is of oval form and the karyo- 

 plasm stains uniformly blue. Nissl bodies occur also in the proximal 

 portion of the axone. The reticular structure of the cytoplasm cannot 

 be seen. In the chromophobes, however, the cytoplasmic reticulum 

 is apparent, while the cell body is on the average larger than the chro- 

 mophiles. The peripheral zone is in many cases comparatively free 

 from chromatic substance and the axone is entirely free from it. 



AVhether these two types are actual or due to functional conditions 

 VAN Durme is not positive, for, as he points out, it is impossible to 

 find all the cells of the nervous system in a condition of absolute rest. 

 He finds, accordingly, that in rabbits which have been killed in the 

 early morning there is great variation in the proportion of the two 

 types of cells. 



For studying the condition of the cerebral and cerebellar cells 

 during activity and fatigue van Durme stimulated these regions indi- 

 rectly through the spinal cord with electricity. He examined the 

 cerebrum and cerebellum after continuous stimulation of the cord for 

 periods of five minutes, thirty minutes, two and one-half and seven 

 hours. He concludes from his experiments that abundance of chro- 

 matic substance and an oval nucleus are characteristic of the condition 

 of rest. x'Vctivity is accompanied by a reduction of chromatic sub- 

 stance in both the cell body and the nucleus, and an increase in vol- 

 ume of the cell body and nucleus. Fatigue, in like manner, is char- 

 acterized by the presence of cells extremely impoverished of chromatic 

 substance and rich in vacuoles. The author's explanation of this proc- 

 ess is noticed in a following paragraph. 



Regarding functional changes in the nerve cell of the cerebral 

 cortex, Geeraerd has experimented upon the guinea pig. To produce 

 fatigue he employs natural methods in preference to artificial stimuli 

 such as electricity, which, he believes, is highly objectionable. His 

 argument against it, indeed, seems rational. He recognizes that under 

 natural conditions there is a physiological barrier to over-stimulation 



