174 Recently published Ornithological Works. 



Seligmann and Shattock on Spermatogenesis in the Mallard. 



[Observations made to ascertain whether any relation subsists between 

 the seasonal assumption of the " eclipse " plumage in the Mallard {Anas 

 boscas) and the functions of the testicle. By C. G. Seligniarln, F.Z.S., 

 and S. G. Shattock. Proc. Zool. Soc. 1914, pp. 23-43, text-figs. 1-6.] 



The object of the observations and experiments described 

 in this paper were to endeavour to ascertain what relations . 

 existed between the periods of sexual activity of the testicles 

 of the Mallard and of the plumage-changes, and whether 

 these two phenomena had any causal relation to each other. 



Two series of observations were undertaken. Of these 

 the first consisted in the simultaneous examination of the 

 plumage and the condition of the testes in a series of Wild 

 Ducks during any month in the year ; the other of obser- 

 vations on Wild Ducks which had been castrated. 



The conclusions arrived at are that the periods of activity 

 and non-activity of the testes do not coincide with the two 

 seasonal changes of plumage. The testes normally attain 

 their maximum size in March or April, while the eclipse 

 plumage is assumed in July and passes off in September. 

 If, however, castration is carried out during the months when 

 the testes are assuming or have assumed their functional 

 activity, the assumption of the eclipse plumage is delayed, 

 and in some cases is not assumed at all. Great difficulty, 

 however, was found in completely performing the operation 

 of castration, and in almost all birds examined, which had 

 been previously so treated, small nodules or grafts of re- 

 generated testicular tissue were found. 



Shufeldt on the Eggs of Humming-birds. 



[Reder og Aeg af Nordamerikanske Kolibrier (Trochili). Af R. W. 

 Shufeldt. Med Tavle ii.-viii. Dansk ornith. For. Tids. viii. 1914, 

 pp. 187-195.] 



The veteran American ornithologist Dr. Shufeldt has 

 written a general account of the nests and eggs of the 

 Humming-birds of North America for the Danish Ornitho- 

 loo-ical Journal. The photographs which illustrate the 

 paper are apparently taken by the author himself from a 



