Varietäten etc. — Physiologie. — Palaeontologie, 549 



A. W. Gilbert. (New York, The Macmillan Company, $ 2.00. 

 Duodecimo. pp. XVIII, 474. 113 ff. 1915.) 



One of the Standard "Rural Science Series", revised and brought 

 up to date by the Professor of plant breeding at Cornell University. 

 The Contents fall under the chapter headings "The fact and philo- 

 sophy of Variation", "The causes of individual differences", "The 

 choice and fixation of variations", "Mutations", "The philosophy of 

 the Crossing of plants, considered in reference to their improvement 

 under cultivation", "Heredity", "How domestic varieties originate", 

 "Pollination, or how to cross plants", and "The forward movement 

 in plant breeding". 



Five appendices are concerned with a glossary of technical 

 plant breeding terms, plant-breeding books, a list of periodicals 

 containing breeding literature, a bibliography, and a series of 27 

 laboratory exercises. A rather brief index closes the volume. 



Trelease. 



Vestepgaard, H. A. B., Jagtagelser vedrörende bladgrönt- 

 löse Bygplanter. [Beobachtungen über chlorophyllfreie 

 Gerstenpflanzen]. (Tidsskr. Planteavl. 21. p. 151. Kopenhagen. 

 1914.) 



Bei Linienkulturen von Gerste beobachtete der Verf., dass eine 

 Linie 24.5% weisse Individuen enthielt. Die weissen Pflanzen starben 

 bald ab. Bei Kulturversuche mit den übrig gebliebenen grünen 

 Pflanzen wurden auch in den folgenden Jahren weisse Individuen 

 abgespalten, aber in sinkendem Prozent zahl. Die Mutterpflanze der 

 betreffende Linie war somit ein „Mutationsbastard". 



P. Boysen-Jensen. 



Caveps, F., Gola's Osmotic Theory of Edaphism. (Journ- 

 Ecology. II. 4. p. 209—231. 1914.) 

 A most useful coUective summary on the coUoidal properties 

 of soils. Since the term coUoid was introced by Graham in 1861, 

 considerable advances have been made, and the progress is here 

 briefly sketched up to Van Bemmelen's investigations on clay 

 coUoid's, and those of Baumann and others on humus coUoids. 

 The main object of the paper is with reference to several memoirs 

 by Gola, which the author considers have been rather overlooked 

 by ecologist. Two of these have been summarised in great detail: 

 1) "Studi sui rapporti tra la distribuzione delle piante e la consti- 

 tuzione fisicochemica del suolo" (Ann. di Bot. 3, 1905); 2) "Saggio 

 di una teoria osmotica dell' edafismo" (ibid 8, 1910). Gola's general 

 arguments are summarised, including the distribution of soil col- 

 loids — hydrosols and hydrogels — in various types of soils and 

 substrata, the effects of physical structure of the soil, Variation in 

 water content, and the influence of a covering of Vegetation. Gola's 

 Classification of plant habitats is carefully stated and illustrated, so 

 that the somewhat cumbrous terminology is shown to have its ad- 

 vantages; for details reference should be made to the original. 

 Gola's "Laws of the edaphic distribution of plants" are also outlined. 



W. G. Smith. 



Andersson, G., Japetus Steenstrup och Torf mosseforsk- 

 ningen. [Japetus Steenstrup und die Torfmoorfor- 



