158 



NA rURE 



[December 9, iqoo 



I would like to suggest that this colouring of eggs was 

 in some way originally analogous to the change of colour 

 observable in the chameleon and certain lizards, though 

 by no means at the same level of development. Although 

 it is quite possible that the colouring in some cases is 

 protective, or has become so, it does not seem that this 

 is a fixed rule. Why should the egg of a starling, which 

 generally builds on house-tops, be blue? The hedge- 

 sparrow's, again, is blue, while the thrush's is blue spotted 

 with black, and the blackbird's is green, though the posi- 

 tion of their nests is vastly similar. Again, on examining 

 the excellent "clutches" at the Natural History Museum 

 which exhibit the additional cuckoo's egg, one is struck 

 by the variation in shade, which, according to observers, 

 is matched by the bird itself. 



It seems to me that the elucidation of this problem would 

 be of great value in such vexed questions as the inheritance 



THE PROPHYLAXIS OF TROPICAL DISEASES. 



THE history of tropical medicine, or what might be 

 called its recent twentieth century renaissance, 

 will go down to posterity as one of the most remark- 

 able chapters in medicine. In a book entitled " Mos- 

 quito or Man? The Conquest of the Tropical 

 World,"! Sir Rubert Boyce endeavours, in his own 

 words, to epitomise this wonderful movement, a move- 

 ment initiated in England by the then Secretary of 

 State for the Colonies, Mr. Joseph Chamberlain, and 

 by Sir Patrick Manson, a physician who had practised 

 in the East, and had returned home imbued with 

 the idea that the diseases of the tropics stood, so to 

 speak, by themselves, and thus required special teach- 

 ing in the medical schools of this country. The idea 



of acquired characteristics, and might be really illustrative 

 of the exact processes of evolution. R. L. Leslie. 



13 Electric Mansions, Brixton, S.W., December i. 



The Terminal Velocity of Fall of Small Spheres in Air. 



At the recent Winnipeg meeting of the British Associa- 

 tion we presented some results on the terminal velocity of 

 fall of approximately spherical spores, which were not in 

 agreement with Stokes's formula (see Nature, October 14, 

 p. 472). We have succeeded since in making minute 

 spheres of paraffin wax, a certain black wax, and mercury, 

 and have determined their terminal velocities over a wide 

 range of sizes by the same method as in the preceding 

 investigation. The velocities obtained for these spheres are 

 in close agreement with Stokes's formula. The reason for 

 the deviations in the former cases is not clear. 



John Zeleny. 



L. W. McKeeiun. 

 University of Minnesota, November 23. 

 NO. 2093, VOL. 82] 



gained ground; two tropical schools, one in London, 

 one in Liverpool, were founded, as Sir Rulxrt describes 

 in his first chapter, and from that day onwards things 

 have never looked back. Discovery after discovery 

 have poured from these schools until now we stand on 

 the threshold of a new world, a tropics as healthy as 

 a temperate clime. 



There apparently is nothing new under the sun, not 

 even in medicine; the author describes in his fourth 

 chapter how Sir Henry Blake, when Governor of 

 Ceylon, had been shown a medical work written four- 

 teen hundred years ago, in which the mosquito was 

 stated to be a carrier of disease, and in which malaria 

 was described as being transmitted by flies or mos- 

 quitoes — a truly prophetic utterance. More recently 

 than this certainly, but yet, as things go now, of older 



1 "Mosquito or Man? The Conquest of the Tropical World. By Sir 

 Rubert Boyce, F.R.S" Pp. xvi+267. (London : John Murray, 1909.) 

 Price 10s. 6d. net. 



