Critical Digest. Irii 



by dissolution ; and he adds (3) neurones of a third category — Ra- 

 mon y Cajal's cells of the cortex — with several short ascending neu- 

 rites. He admits all the possible transitions between the first two cate- 

 gories. It would seem wiser to give up categories of this formal kind 

 and to proceed to describe the known cell-types without an effort to 

 force the unknown or incompletly known types into an a priori as- 

 sumed number of categories, v. Monakow does not make a more 

 than schematic use of his classification in the subsequent chapter on 

 the general architecture of the nervous system. Chiefly from the 

 point of view of experimental degenerations he gives us the types of 

 gray matter, evidently without due references to more delicate stains 

 than carmine. Apart from this defect, the method deserves great 

 praise and might well be widely adopted in principle at least. So much 

 attention has been paid exclusively to the ' neurone ' that the study of 

 the tissue as tissue is almost an unknown quantity to the modern gen- 

 er;<,tion — to its great disadvantage. Just in this direction, v. Mona- 

 kow's work has a merit which greatly outdoes the few small defects 

 mentioned above. It is his effort to bring before us true tissues such 

 as he has learned to know them in his untiring experimental and pa- 

 thological work. For the first time we find some of the most vital 

 points in the understanding of nervous pathology made accessible in 

 a hand-book. The importance of this step of v. Monakow is so great 

 that we enumerate here his types of gray matter : 



1. The type of the motor nuclei so-called, including the real 

 motor nuclei of the spinal cord and bram-axis and also nuclei the mo- 

 tor character of which is not established : nucleus ruber tegmenti, 

 Deiters' nucleus lateralis, v. Gudden's nucleus, the lateral nucleus of 

 Burdach's columns etc. — (With the use of the Nissl method, this first 

 type must necessarily be split into several types.) Section of the nerve- 

 fibers coming from these cells causes the cells to atrophy (or at least 

 to react in a characteristic manner) . 



2. The type of the gray of the sensory terminal nuclei. De- 

 generation of the afferent fibers causes the intermediate or ground-sub- 

 stance to atrophy and the cells of the nucleus to become more 

 crowded, v. Monakow seems to put rather too exclusive weight on 

 the presence and importance of the cells of Golgi's second category, 

 especially in the paragraph speaking of 



3. The type of the head and spinal ganglia, including the sym- 

 pathetic. 



4. The gray of the nuclei of the optic thalami and the parts de- 

 pendent on the fore-brain — substantia nigra, certain elements of the 



