July i, 1920] 



NATURE 



545 



performance of an immoral act. If prostitution 

 could be abolished, venereal disease would prob- 

 ably in time become extinct, but no means have 

 yet been discovered by which, mankind being what 

 it is, prostitution can be abolished. 



All the authors alike urge propaganda. The 

 National Birth-rate Commission thinks that the 

 Ministry of Health should direct the attention of 

 the public to the urgent duties of citizens 

 in the matter. Dr. H^ricourt says that we 

 must act upon the will of the individual by 

 persuasion through fear and through interest, 

 and mentions a work by Prof. Fournier 

 that has been circulated by the French Society 

 for Sanitary and Moral Prophylaxis as well 

 calculated to effect the desired persuasion. 

 Mr. Miall, who adds a chapter of his own to his 

 translation of Dr. H^ricourt's work, urges that 

 proper instruction should be given in the dangers 

 of venereal disease. Mr. Burke, who has been 

 an acting lieutenant-colonel in the Royal Army 

 Medical Corps, argues forcibly that the public 

 must be made more acquainted with sexual 

 matters, increase its knowledge of the pre- 

 valence and dangers of venereal disease, and 

 be induced to appreciate and to assist actively 

 in the means to be provided for treating 

 and finally stamping out of existence those 

 disorders. The education, he says, must begin 

 with the child. The adult must be impressed with 

 the importance, the reality, and the dangers of 

 venereal disease. The medical profession must set 

 its teeth with determination to fight the menace 

 out of existence. Mr. Burke's treatise, which is 

 illustrated by six diagrams, is likely to be of value 

 in effecting the common purpose of enlightening 

 the public on these important matters. E. B. 



The Elements of Hardy Fruit Culture. 



Practical Hardy Fruit Culture. By Richard 

 Staward. Pp. 216. {London: The Swarth- 

 more Press, Ltd., 1920.) Price 65. net. 



ALTHOUGH in many respects this small 

 treatise on hardy fruit culture may be com- 

 mended to beginners as a clear, concise, and ele- 

 mentary guide on the subject as applied to garden 

 conditions, describing methods followed' with 

 success by the author at Panshanger Gardens, 

 Hertford, it cannot be considered as having 

 achieved the main purpose for which it was 

 written. The author has set himself to provide a 

 useful book for those, forming a numerous class 

 at the present time, who are adopting hardy fruit 

 culture as a business and know little or 

 nothing of such work. The methods recom- 

 NO. 2644, VOL. 105] 



mended, however, are essentially those for the 

 private gardener, as distinct from the commercial 

 fruit-grower. Taking the case of distances for 

 planting trees as an example, it is advised that 

 bush or pyramid apples on free stocks should be 

 planted 12 ft. apart, and those on the Paradise 

 stock from 6 ft. to 9 ft. apart. For standard 

 apple-trees 12 ft. is mentioned as the dis- 

 tance, if space is limited. For commercial work 

 these distances should be at least doubled for 

 varieties of vigorous growth, where the trees are 

 to be treated as permanent and not as fillers. A 

 general criticism may also be made of the lists 

 of varieties recommended, which are almost in- 

 variably too long, and contain sorts which are of 

 at least doubtful commercial value. 



The sections devoted to the diseases and pests 

 of the respective fruits make mention for the most 

 part of the more serious troubles, and of some 

 which are relatively trivial; but there are im- 

 portant omissions, such as silver-leaf of plums, 

 bitter-pit of apples, and reversion of black-currants. 

 The remedies proposed are typical garden methods 

 and are often inappropriate for commercial 

 plantation use. In some cases they would appear 

 to miss the mark entirely, as when, for instance, 

 the spraying of black-currants with lime-sulphur, 

 or, as the author describes it, "bisulphide of cal- 

 cium," against big-bud-mite attack is advised after 

 the fruit has been gathered. By that time the 

 mites are safely within the cover of the newly 

 formed buds. It may also be questioned whether 

 the author has made the best use of the space at 

 his disposal by dealing with such fruits as out- 

 door grapes, mulberries, medlars, and apricots, 

 by description of methods of propagation which 

 are not adopted in general practice, and by de- 

 tailed accounts of the training of special forms of 

 trees which are never considered except for par- 

 ticular purposes in private gardens. 



The illustrations are original, and some are of 

 interest. 



Our Bookshelf. 



Experiments in the Breeding of Cerions. By 



Paul Bartsch. (Department of Marine Biology 



of the Carnegie Institution of Washington. 



Vol. xiv.) (Publication No. 282.) Pp. 55 + 59 



plates. (Washington : The Carnegie Institution 



of Washington, 1920.) Price 3 dollars. 



Cerions are land snails, well represented in the 



Bahamas by five species. They occur on the 



ground, under the edges of stones, among dead 



leaves, on grass, and on bushes. On an exposed 



place they attach themselves to the support by a 



\ thin epiphragm which also serves to prevent 



