STUDIES IN THE EXPERIMENTAL ANALYSIS OE SEX. 45 
Studies in the Experimental Analysis of Sex. 
B j 
Geoflrey Smith, UI.A., 
Fellow of New College, Oxford. 
(From the Department of Pathology, University of Oxford.) 
With Plates 6-9 and 5 Text-figs. 
Part 6. — On the Cause of the Fluctuations in Growth of the 
Fowl’s Comb. 
In Part 5 of these studies (‘ Quart. Journ. Micr. Sci./ vol. 56, 
pt. 3, 1911, p. 591) some observations on the fluctuations in 
size of hens’ combs were recorded, which showed that in adult 
as well as in young hens the area of the comb may increase 
or decrease with great rapidity, the greatest increase recorded 
being 130 per cent, within three weeks. It was proved that 
these striking fluctuations were independent of any experi- 
mental treatment, that they did not correspond with a 
general increase in weight, and that they appeared to coin- 
cide with the egg-laying periods. 
The object of this paper is to prove that the correspondence 
of the comb-increase with egg-laying is invariable, thus con- 
firming by accurate measurements the rough empirical rule 
by which poultry breeders are accustomed to predict when a 
hen is about to lay. We shall also show that these rapid 
fluctuations are characteristic of hen birds, and that they are 
due to a fatty infiltration of the central core of the comb 
taking place just before egg-laying commences. Before 
VOL. 57, PART 1. — NEW SERIES. 4 
