675 
relation of volume of the plasm would remain the same. We arrive 
therefore at the following statement: 
The plasm volume of the nerve cell varies in proportion to the cube 
root of the body weight, te. to the mean linear dimension of the body. 
Hence we are justified in considering the plasm volume of the 
nerve cell as determined dynamically. The mean linear dimension of 
the body varies in inverse ratio to the rapidity of the movements, 
and in direct ratio to the duration of the muscle contractions (com- 
pare the Cat and the Tiger), because the muscular force, which is 
determined by the transverse section of the muscles, and the body 
weight are in this proportion. 
The calculated values of the exponent 4, in the equation for the 
variation of the nucleus-volume with the cell-volume, are given in 
the third column of Table IT. It appears that most of these values, 
and their mean, are slightly below 2/3, which value £ ought to have, 
if the variation of the nucleus volume were proportional to the 
surface area of the cell. We may assume 0.6 or 3/5 for the real 
value of &. This lies exactly halfway between that for proportio- 
nality with the area of surface of the cell and with the area of 
surface of the nucleus, that is the outer and the inner surface of 
the plasm. This leads to the conclusion that the regulation of the 
metabolism of the plasm of the ganglion cell must be attributed to 
the nucleus. Apparently we are, therefore, justified in considering 
the nucleus as the assimilator and dissimilator of the plasm — by 
catalysis or enzyme action, — and as the process of stimulation in 
the nerve fiber undoubtedly proceeds from (or ends in) the plasm, 
which is closely connected with the axone, the name of neurokinete 
may be applied to the nucleus. *) 
Further, it can be deduced from the value found for Z, that the 
volume of the nucleus varies proportionally as P16 op Pile, and 
the square of the volume of the nucleus as the volume of the plasm 
of the cell. Hence these two are in the same relation to each 
!) The action of the same enzymes can give rise both to synthesis and analysis. 
P. Scuterrerpecker (Muskeln und Muskelkerne, Leipzig 1909, p. 150 et seq.) 
found that in the rabbit the relative nuclear volume of the red muscle fiber, 
which is rich in muscle haemoglobin, is much greater than that of the while 
muscle fiber, which is poor in muscle haemoglobin. In the red Soleus the relative 
nuclear volume is 2'/, times greater than in the white Gastrocnemius, which 
consists of muscle fibers of similar form, and which acts in conjunction with the 
Soleus. This, too, points to a catalytic relation between the nuclear quantity and 
the rapidity of the metabolism (oxygen consumption) of the cell. 
