ApRll.21, 192 I ] 



NATURE 



245 



the reason of the anti-vaccinationists. " It would ap- 

 pear," she says, "to be advisable to substitute argu- 

 ment for compulsion." She deals in some detail with 

 the "Leicester experiment." "The Leicester method, 

 -as advocated bv Dr. Millard, includes vaccinations as 

 general as possible when an outbreak occurs." When 

 Dr. Scharlieb says, "The incubation period of vac- 

 cinia is shorter than that of variola, eight or nine 

 •days as against twelve," the words imply that these 

 are two distinct diseases. The modern view is that 

 "vaccinia" is simply the effect of inoculating the 

 •cow or calf with smallpox virus, an3^is not any more 

 a separate disease than human tuberculosis inoculated 

 on a cow would be. But the virus, cultivated on the 

 calf through several generations, loses its capacity 

 to produce general infection. As this is a cardinal 

 point in the anti-vaccination argument, the Research 

 Defence Societv might well devote a sf>ecial paper to 

 it. The "portion of the Gloucester cemetery" shown 

 as frontispiece is an eloquent comment on Nature's 

 way with the unvaccinated. 



We note with much satisfaction that Major Stanley 

 Flower's efforts to restore the well-nigh exterminated 

 cattle-egret to Egypt have been abundantly rewarded. 

 Mr. J. L. Bonhote, in the Report on the Zoological 

 Service for the Years 1914-18, published in connection 

 with the Giza Zoological Gardens, gives a long and 

 able summary of the steps taken to bring about this 

 much-to-be-desired end. When this apparently hope- 

 less task was begun the bird had been all but exter- 

 minated by plume-hunters. Mr. Bonhote is now able to 

 report colonies numbering several thousands, and the 

 birds appear to be still extending their range. In this 

 achievement, made possible by the enlightened action 



• of Lord Kitchener when British Agent and Consul- 



• General, Major Flower has rendered a signal service 

 to Egypt, for the cattle-egret as a destroyer of ticks 



• on cattle and of noxious insects of many kinds has no 

 rival, and therefore the establishment and preserva- 



'tion of large colonies of this bird are of vital import- 

 .-ance to the country. 



That the woodcock will, on occasion, transport its 

 young by carrying them in mid-air is now a well- 



• established fact. A few other species are said to 

 have been seen performing this feat. Mr. J. H. 



'Gurney in the April issue of British Birds writes to 

 say that on May 12, 1920, he found a long-eared owl 



• covering "four young ones under a gorse bush. "The 

 situation was somewhat unusual, and so was her 

 subsequent behaviour, for she carried two of her nest- 



■ lings, in consequence of their being" looked at, more 

 than twenty yards and deposited them on a pair of 

 } oung Scotch firs, where they presented a very 



■comical appearance." It would be interesting to 

 know whether she carried off the remaining nestlings 



• to the trees or transferred the two in the trees 

 ' back to the nest when the cause of her alarm 



was removed. In the same communication — " Ornitho- 

 logical Notes from Norfolk for 1920" — Mr. Gurney 

 shows that at least two pairs of bitterns reared young 



' in Norfolk during that year. This, indeed, demon- 

 strates the efficiency of the protection afforded to 



' rare breeding birds in Norfolk. 



NO. ^686, VOL. 107] 



In an article entitled "Facts about Rattlesnakes," 

 published by the Los Angeles Times, and copied by the 

 Dallas Saturday Night of June 26, 1920, Mr, W. S. 

 Griswold describes many of the peculiar habits of these 

 snakes. The commensal trait in Crotalus cerastes is 

 certainly the most interesting. The horned rattlesnake, 

 the author observes, takes up its abode in the burrow of 

 a prairie-dog, which burrow is also sometimes shared 

 by the small prairie-owl, all these three creatures 

 living amicably together. He explains that the 

 prairie-dogs' holes form the only possible shelter in 

 the arid plains, and that being always near water 

 they make doubly attractive retreats. " In return for 

 this hospitality the rattlesnake," it is remarked, 

 " takes charge of the census, and thoughtfully pre- 

 vents the prairie-dog from accumjulating a larger 

 family than he can conveniently support." According 

 to Dr. Gadow, this instance of commensalism is an 

 exaggeration, the original inhabitants deserting the 

 hole when the rattlesnake intrudes. Mr. Grisvvold's 

 version is, however, quite credible when one considers 

 the case of the Tuatara lizard, which excavates a hcJe 

 which it shares with a petrel, and, although invariably 

 tplerant pf the petrel and its farnily, will not allow a 

 second Tuatara to enter. 



A CORRESPONDENT who travels frequently from the 

 south-west of England to London states that, in his 

 opinion, at this time of year vegetation, notably the 

 flowering-trees, is generally more advanced as the 

 metropolis is approached, and he asks whether others 

 have made similar observations. Mr. J. Edmund 

 Clark, who is largely responsible for the phenological 

 reports of the Royal Meteorological Societv, has very 

 kindly forwarded us some particulars bearing- upon 

 the subject which do not appear to support our cor- 

 respondent's statement except in the case of the hazel. 

 The following are, for example, the dates of flowering 

 for some trees during 19 19 in south-west and south- 

 east England : 



Horse- 

 Hazel Blackthorn chestnut May Rose 

 S.W. England ... Feb. 9 March 31 May 2 May 10 June 6 

 S.E. „ ... ,, 3 April 5 „ 7 „ II „ 6 



Records for 1920 are not yet available. The figures, 

 of course, give no trustworthy indication of the time 

 of flowering of cultivated fruit-trees, which probably 

 constitute the greater part of the flowering trees in 

 the neighbourhood of London. 



If segregation of Mendelian factors is determined 

 by the separation of pairs of chromosomes during 

 germ-cell formation, then there should be no Men- 

 delian segregation in parthenogenetic eggs in which 

 the full chromosome complement is retained. Prof. 

 W. E. .■^gar has adduced further evidence on this point 

 (Journal of Genetics, vol. x., No. 4) in a continuation 

 of his breeding experiments with the Cladoceran 

 Daphnia, which reproduces for the most part partheno- 

 genetically. In a cross between D. obtiisa and D. 

 pulex, one of the hybrid offspring was bred partheno- 

 genetically for ten generations. The most con- 

 spicuous difference between the species is in the rela- 

 tive lengths of two of the abdominal spines. The F, 

 hybrid was intermediate as regards this ratio, and 

 statistical treatment of the measurements of its 



