48 INTERNAL SECRETIONS 



true for other species, as, for instance, for the partridge, 

 where the male and the female have a very similar plumage. 

 On the other hand certain facts may be explained on the 

 assumption that the ovary does not always inhibit the develop- 

 ment of the plumage and the spurs of the asexual type. There 



Fig. 34A. Normal Sebright Cock. 



— From T. H. Morgan. 



are some birds in which the females have fully developed male 

 plumage, as for instance, in the cases of the pheasant known 

 as Crossoptilum auvitum and the thistle-finch.^ There are 



* In the thistle-finch or goldfinch "both sexes are similar; only a very 

 practised eye can distinguish the female from the male by the somewhat 

 greater size, by the slightly larger quantity of red on the front of the head, 

 and by the darker black on purer white on the back of the head" {Brehm, 

 Vol. IX., p. 423). Mrs. L. told me that in her youth she often wondered at 

 seeing two "male" thistle-finches constantly together. The female was 

 mistaken for a male I An almost complete similarity between the plumage of 

 the two sexes seems to occur in the finch of Turkestan [Cardualis caniceps), 

 as I learned from the specimen in the natural history museum in Berne. Of 

 Crossoptilum auritum, Brehm (Tierleben, vol. VII., 4th ed., Leipzig, 191 1 

 p. 77) says: "Both sexes are of the same colour." 



