April. 1911. 



kxowl1':dge. 



157 



ZOOLOGY. 



By Proi-hssor J. Arthur Thomson. 



THE BIOLOGICAL HOROSCOPE.— Professor D. H. 

 Tennent, of Bryn Mawr, has been very successful in crossing 

 sea-urchins of different genera, Toxopiieitstes and Hippoiiuc. 

 The To.\opneustes influence dominates in sea-water of a 

 higher OH ion concentration, and the Hipponoe influence 

 dominates in sea-water of a lower OH concentration. It is 

 suggested that this variation in the sea-water, brought about 

 artificially in the laboratory, may correspond to normal 

 seasonal changes. If so, it throws light on the difference 

 previously observed between the winter embryos and the 

 summer embryos of the cross between Spliaerccliiniis and 

 Stroll jiylocetitrotiis. Thus something depends on the season 

 of birth, and thus we come back to the horoscope and 

 astrology — in new guise, of course. 



SPARROWS AND POULTRY. — The poultry -raising 

 industry in many parts of the United States is seriously 

 menaced by "blackhead" and similar diseases due to parasitic 

 Protozoa known as Coccidia. Philip H. Hadley has found 

 that these parasites are abundant in the intestinal tract of the 

 English Sparrow, which he therefore blames for the diffusion 

 of the disease. The parasite occurs also in some other wild 

 birds, such as the American "robin" iMcriila inigratorinK 

 and severe coccidiosis has been observed in the quail {Col nuts 

 virginianiis) and the grouse [Boiiaso uinbcllatus). Thus 

 wild game birds as well as poultry (fowls, turkeys, ducks, geese, 

 pigeons, pheasants, guinea-hens) are seriously threatened. 



LEPTOMONAD IN EUPHORBIA.— Not long ago Lafont 

 made the remarkable discovery that the late.x of Euphorbia 



pilulifcra in Mauritius contained as a parasite a species of 

 Lcptonionas, that is to say, a kind of parasite characteristic 

 of animals, and next door to Trypanosomes which cause 

 sleeping sickness and the like. This very interesting dis- 

 covery has been confirmed by G. Bouet and E. Rouband in 

 regard to other species of Euphorbia. They find the infection 

 local, temporary, and without obvious pathological effects. 

 They were led to regard a small Hemipterous insect, D/c7(c/j<.'s 

 hiiiiiilis, as the infecting agent, but fresh experiments by 

 Lafont, in the case of Euphorbia pilulifcra, point to another 

 bug, Xysiiis fupliorbiac. as the culprit. 



CILIARY AND MUSCULAR MOVEMENTS.— Looking 

 down from the rocks into the water in the summer seaSon 

 one often sees a jellyfish and a Ctenophore moving together, 

 both very beautifully, but in very different ways ; for the 

 jellyfish is moving mainly by muscular contraction and the 

 Ctenophore by cilia. It has been shown by A. G. Mayer, 

 in a series of interesting papers, that these two kinds of 

 movement have a converse relation to one another. Thus 

 sodium is the most potent check to ciliary activity and the 

 most powerful neuro-muscular stimulant. Magnesium is most 

 potent in maintaining ciliary movement and the most powerful 

 inhibitor of neuro-nniscular movements. Among reagents of 

 this sort whatever stimulates cilia depresses muscular activity, 

 and whatever inhibits muscular movement stimulates cilia. 

 In nature the more highly specialised cilia, such as those of 

 the Ctenophore's combs, which are under the control of the 

 neuro-muscular system, stop whenever the muscles contract 

 and beat only when the muscles are relaxed. " The dis- 

 covery of this converse relation makes very apparent the 

 incompleteness of all existing explanations of the cause of 

 animal movements." 



REVIEWS. 



CHEMISTRY. 



Xcw Rcdiictiiui Mcfhoits III \'(>lii iiicfnc Analyses. — By I'.. 

 Knecht, Ph.D.. EM. C. and E\a Hibbert. lOS + x. pages. 



(Longmans. Price 3 - net. I 



This little volume gives, in an accessible form, the numerous 

 papers published by the authors in different journals upon the 

 use of titanous chloride in volumetric analyses. Solutions of 

 this salt can now be readily obtained in a fairly pure condition 

 and its very powerful reducing properties render it particularly 

 suitable for use in the volumetric estimation of all kinds of 

 compound. Full descriptions of the methods of using it are 

 given here, and in the case of some of these estimations there 

 had previously been no reliable process of determining the 

 substance in question. In particular, the application of this 

 compound to the quantitative estimation of various dyestuffs 

 will be found especially useful. The book will prove a 

 valuable addition to the librarv of c%erv laboratory. 



BIOLOCiY. 



r/(c' Origin of Species by Means of Natural Selection 



(Popular impression of the copyright edition). — By Charles 



Darwix. 432 pages. 7T-in.X5-in. 



(John Murray. Price 1 - net.) 



" The Origin of Species " has now passed out of copyright, 

 but the edition which it is now open to anyone to print is the 

 unrevised one which was superseded by the present one. Mr. 

 Murray is to be congratulated on bringing out the popular 

 impression at a price which is within the reach of everyone. 



BOTANY. 



Life Histories of Ediiiiliar I'lants. — By Jc.iHN J. Ward, 



E.E.S. 204 pages. iS6 plates. S-in. X5-iu. 



(Cassell & Company. Price 3/6.) 



This popular edition will give Mr. Ward's delightful essays 

 on the familiar plants a wider circle of readers and will help 

 on the great movement that is proceeding, whereby the public 

 generally is being interested in the world of life around it. 



Open Air Studies in Botany. — Second edition. By Robert 



Lloyu Praeger, B.A. 266 pages. 58 illustrations. 



8-in.X 5t-in. 



(Charles Griffin & Company. Price 6/- net.) 



We are pleased to see that a second edition of Mr. Praeger's 

 book has been called for as it is not occupied with the 

 dry-as-dust Botany, but with sketches of British wild flowers 

 in their homes among the shingle, by the river, in the meadow, 

 among the corn and along the fragrant hedgerow. Those who 

 know Mr. R. Welch's photographs will know that the plates 

 well illustrate the plant associations and habitats with which 

 they deal. 



Aids to Bacteriology. — Second edition. By C. G. IvIoor, 



M.A., and WiLLL\M Partridgi;. 240 pages. (6i-in. X4-in.) 



(Baillierc. Tindall & Cox. Price 3'6 net.) 



This book is a second edition of a little work dealing briefly 

 with a great number of points coming under the heading of 

 Bacteriology. In the Introduction general matters ai'e con- 

 sidered and the various bacteria of disease, methods of 

 examining them, forms producing fermentation, and the 

 bacteriology of every-day life are briefly touched upon. 



