1 82 Journal of Comparative Neurology and PsyeJiology. 



OFF ('98) observes that the genimules are lost in varying degrees in the 

 nerve cells of animals subjected to poisoning by arsenic, rabies, tuber- 

 culin and also of animals suffering from thyroidectomy. These studies 

 were checked by preparations of nerve cells from a normal guinea 

 pig killed by decapitation. The nervous tissue was quickly placed in 

 the fixing reagents and received like treatments with the abnormal 

 tissues. The preparations showed gemmules present almost univer- 

 sally upon the dendrites. 



In collaboration with Czarniecki, Soukhanoff ('02) has studied 

 the dendrites of the ventral horn cells of the rabbit with the Golgi 

 method. By killing the animals quickly with chloroform the authors 

 considered that the tissue was found in the normal condition. 



Upon the dendrites of certain cells very few gemmules were 

 found ; in others they were numerous, beginning to appear on the 

 dendrites nearer the cell body and becoming more numerous as the 

 distance from the perikaryon increased till in the distal region they al- 

 most covered the process. In another type of cell, which lay with the 

 protoplasmic processes partly within the white substance, that part of 

 the dendrite which lay within the white substance bore no gemmules, 

 while the part lying within the grey substance was abundantly supplied 

 with them. And even when the dendrite lay in the border line between 

 the grey and the white substance the side of the dendrite which faced 

 the grey bore more gemmules than did the side facing the white. The 

 authors conclude that the gemmules are much less numerous upon the 

 ventral horn cells than upon the cells of the cerebral cortex, but that 

 they are much more variable in size and shape. They may be pyri- 

 form, filamentous, club-shaped, tubercular, or finely branched. Cer- 

 tain of these forms which the authors call "rejitons," which are very 

 irregularly fibrillar and club-shaped, are not found in the cells of the 

 cerebral cortex. 



Geier ('01) has studied with the Golgi method the cerebral cortex 

 of mammals and birds which have been subjected to the vapors of 

 ether and chloroform for from five to ten minutes. In some of the 

 experiments the gemmules showed a tendency to disappear, while in 

 others the cells appeared perfectly normal. The disappearance of the 

 gemmules was found to be concomitant with the moniliform condition 

 of the dendrites. As Geier considers the moniliform condition of the 

 dendrites as morbid, due probably to exhaustion or want of nutrition, 

 he would also interpret the disappearance of the gemmules as indi- 

 cative of morbid processes in the cell. 



In a later work Geier ('02) described the development of the pro- 



