CH. XVII.] NISSI/S GRANULES 201 



into the dendrons, but not into the axon. The substance of which 

 they are composed is termed chromatoplasm, or chromophilic material. 

 The existence of granules in cells which have an affinity for basic 

 dyes like methylene blue is not at all common ; the granules in the 

 majority of the white blood corpuscles, for instance, have an affinity 

 for acid dyes. Micro -chemical methods have shown that the main 

 constituent of the Nissl granules is nucleo-proteid. The name kineto- 

 plasm has been given to it by Marinesco in order to express the idea 

 that it forms a source of energy to the cell. It can hardly be denied 

 that the substance of which the granules are composed, forming as 

 it does so large a proportion of the cell-contents, and made of a 

 material in which nuclein forms an important constituent, is intimately 

 related to the nutritional condition of the neuron. Some have even 

 compared it to the granular material, which is present in secreting 

 cells ; in these cells before secretion occurs, the granules accumulate, 

 and during the act of secretion they are discharged and converted 

 into constituents of the secretion. It is stated by some observers 

 that the Nissl granules are used up during the discharge of energy 

 from nerve-cells, and it certainly is the case that if the cells are 

 examined after an epileptic fit, in which there has been a very massive 

 discharge of impulses, the Nissl granules have disappeared, or at 

 least broken up into fine dust-like particles, so that the cell presents 

 a more uniform blue staining (see fig. 214). It is, however, doubt- 

 ful whether this is due to a transformation associated with intense 

 activity, or whether it may not be caused by venosity of the blood. 

 The cells are very sensitive to altered vascular conditions ; anaemia, 

 for instance, produces a similar change accompanied with swelling of 

 the cell, and swelling and in extreme cases extrusion of the nucleus. 

 High fever (hyperpyrexia) causes a very similar change, which is 

 doubtless associated with the coagulation of the proteids of the cell- 

 protoplasm by the high temperature. 



Since attention has been directed towards the Nissl granules, a 

 literature which has become alarmingly vast during the last few years 

 has sprung up in relation to them. This is quite easy to understand, 

 for neurologists have by this sensitive test been able to identify 

 changes in the cells which could not be detected by the previous 

 methods of staining. Thus the cells have been examined in various 

 diseases, and after being subjected to the action of various poisons. 

 In a new subject of this kind there is, as would be expected, consider- 

 able divergence of views, and even the fundamental question has not 

 yet been answered satisfactorily whether the Nissl granules are present 

 as such in the living cell, or whether they are artifacts produced by 

 the fixative action of strong alcohol. The fact that they cannot be 

 demonstrated when the cells are stained by the injection of methylene 

 blue into the circulation before the animal is killed is a very strong 



