A. PEZARD 273 



always relative to the same segments ; the dimensions are given in mil- 

 limeters. It was difficult to secure greater precision than this, nor 

 would that inform us except on the secondary variations not susceptible 

 of modifying the general appearance of the phenomenon. It should 

 be noted, however, that the dimensions relating to length are rela- 

 tively more precise than those having to do with width, since in the 

 former case we were dealing with a larger figure. 



A curve has been plotted representing the variation in length of 

 the comb during regression. This curve may also represent the vari- 

 ation in volume, for the three dimensions were found to be reduced 

 proportionately, as shown by careful observation of the organ in proc- 

 ess of regression, which visibly retains the same form during the 

 period of its etiolation. This observation may, moreover, be mathe- 

 matically verified by measuring the linear dimensions and the weight 

 of the comb (the latter being proportionate to the volume) in normal 

 and in castrated males. The following is an example. 



Nov., 1919. Normal cock. Comb, 73.40 mm. Weight, 8.8 gm. 

 Castrated " " 54.28 " " 3.1 " 



If the proportions of the comb remained the same, the weight should 

 be proportionate to the cubes of the homologous dimensions. This 

 is found to be true.^ 



/73V /40V 8.8 „ 



( — 1 = 2.45 I — ) = 2.91 = 2.84 



^54^ ^28^ 3.1 



We encountered a difficulty in determining the time of regression. 

 Regression, at least when it follows postpuberal castration, occurs 

 immediately after the operation (indicated on the figures as Op). On 

 the other hand, the end of the regressive period is somewhat uncertain. 

 In our experiments we have arbitrarily considered the regression as 

 terminated when the comb undergoes oscillations of no more than a 

 millimeter per week. 



^ This does not mean that the equation between the length of the comb and the 

 time is exactly that between the volume and the time; nevertheless, it is easy to 

 pass from one to the other. 



