A. PEZARD 283 



■ Although there is not absolute equality among the figures of the 

 last column, one cannot fail to be struck by the fact that there is 

 very little difference; in all instances they diverge much less than 

 those of the first two columns, in which the variation is from 0.5 to 

 4.75 and from 1.95 to 12.0. We must admit, therefore, within rather 

 wide limits, the constancy of the product of the time of regression 

 and the constant C, whether the castration is intrapuberal or post- 

 puberal. 



Geometrically, this result is represented by the constancy of the 

 angle of the ordinate and the tangent to the parabola at the point of 

 departure of the regression curve. Furthermore, it follows that the 

 numerical law is represented not only by a parabola, but more ex- 

 actly by segments of homothetic parabolas — an unexpected generali- 

 zation, which gives a remarkable unity to the law with which it is 

 concerned. 



• CONCLUSIONS. 



1. Postpuberal castration is followed in cocks by a regression of the 

 comb; this organ acquires in a few weeks the aspect and dimensions 

 which characterize similar organs of cocks castrated before puberty. 



2. The diminution in the length of the comb is effected according 

 to a simple law, represented geometrically by a segment of a parabola, 

 algebraically by the equation 



L = l + iC{d - tY 



3. Intrapuberal castration demonstrates that during the develop- 

 ment of the comb C and 6 have values very different from those which 

 are furnished by adults, but the product CO is constant. 



4. This constancy indicates that the diverse curves are represented 

 by similar segments of a parabola. 



