ZOOLOGY. 733 



Some are very affectionate over their young, others the reverse ; thus do 

 individuals differ even among ostriches. As a rule, the cock bird forms 

 the nest, sits the longest, and takes the burden of the work of hatching 

 and rearing." 



Testimony is divided as to whether the cock sits invariably at night 

 to the exclusion of the hen. 



On the one side, Dr. W. G. Atherstone, in a work oh ostrich-farming, 

 has said that the sexes "sit alternately, the male at night grazing and 

 guarding the females. During the daytime, the time of the male bird 

 going on the nest varies during the period of incubation, as also does 

 the time between the female leaving the nest and the male taking her 

 place, the exposure and cooliug being probably regulated by the tem- 

 perature of the incubation fever at different stages." 



On the other side, Mr. Biggar maintained that, " contrary to what has 

 been currently understood, and what is still stated even in recent colo- 

 nial accounts, the cock bird sits at night, not the hen.'''' He even urged 

 that " in this peculiarity the hand of Providence may be seen, for the 

 worst enemies of the nest appear at night, and the cock, being stronger 

 and braver, is better able to resist them ; moreover, the feathers of the 

 cock being black, night sitting would not expose him to that exhaustion 

 from the sun's rays which would ensue if he sat during the day ; while 

 at the same time the gray feathers of the female are less conspicuous 

 while she sits during the day." 



Mr. Romanes claimed that the experience at Florence coincided with 

 that at other places, viz, "that the cock bird undertook the whole duty 

 of sitting during the night." 



There is a general tendency — and a natural one — to concentrate at- 

 tention on facts individually observed and to generalize from those, 

 but nature is often very elastic and her impositions are not always with 

 rigid fetters. Truth may pervade opposite statements and the same 

 shield may be quite different on different sides. Professor Moseley has 

 recognized this truth, and suggested that " an interesting subject of 

 inquiry seems to be still open in the matter. It is, how far do the 

 habits of nidification of the ostrich vary in the different climates through 

 which it ranges ? The nest of the ostrich is commonly described as a 

 heap of sand, and so no doubt it is in warm desert regions," but a 

 nest which he saw "at the Cape was carefully built of grass and other 

 warm materials, so as to aid in retaining heat. The birds kept the nest 

 almost constantly covered between them. In warmer regions, how- 

 ever, the hen appears often to leave the nest in the daytime, and it is 

 just possible that when the temperature is very high the hen may not 

 incubate at all, and the cock alone may do so at uight." (Nature, vol. 

 xxvii, pp. 480, 530.) 



The Thrush family. — The thrushes have been re-examined by Dr. 

 Leonhard Stejneger, the learned Norwegian ornithologist, now resident 



