Meyer, Data of Modem Neurology. 255 



allow definite statements from the point of view of pathology 

 and of entities. 



I . The motor neurones. To begin with, we must admit 

 that it is impossible at present to examine wholly one entire 

 motor neurone in the adult on account of the length and irreg- 

 ular course of the processes, and our inability to isolate it com- 

 pletely or to get the whole into one plane. The Golgi impreg- 

 nations do not give as perfect results here as in other cell-types. 

 The cell-types given in Fig. 5 are quite characteristic. It 

 would not, however, be possible to recognize from the outline 

 alone that the cell was motor except when the axis-cylinder 

 going into the nerve could leave no doubt. The Golgi ' stain ' 

 gives a uniform black color to the cell-body and the processes. 

 In reality, we depend in our studies mostly on the stain of 

 the cell body with the Nissl method and on the Weigert stain 

 for the medullated fibers. We give up the attempt of staining 

 all the parts of the cell at once in order to obtain more char- 

 acteristic details. When speaking of disorders of the whole 

 motor neurone, we do so always making an abstraction from a 

 composite picture. We are forced to study one entire nerve 

 or many nerves and muscle-endings in corresponding segments 

 of the neural tube and from the sum of results we abstract the 

 probable picture of entire neurones. Many points derived from 

 histological and experimental experience are tacitly understood 

 in this process. It would be impossible to demonstate to a per- 

 son without any knowledge of the subject that certain cells are 

 in connection with certain muscles except by a whole series of 

 collateral observations. On ground of a number of experi- 

 ences, we have learned to recognize cells which invariably are 

 connected with certain muscles. This is for instance done with 

 perfect satisfaction in the case of the abducens or trochlear ap- 

 paratus of the eye, where one group of nerve-cells, one nerve 

 and one muscle only enter into the formation. In the facial 

 or hypoglossal nerve we have one group of nerve-cells, one 

 nerve and several muscles ; in the oculo-motor, several groups 

 of nerve-cells, one nerve and several muscles, and in the spinal 

 nerves we know that one muscle receives as a rule fibers from 



