f June i, 1916] 



NATURE 



291 



fore the author suggests that it might advantageously 

 be dropped in favour of such well-understood expres- 

 sions as "reaction" or "orientation." It is satisfac- 

 tory to find that he repudiates the endowment of the 

 term " with mystical causal powers." By calling a 

 reaction — say to light — a "tropism," one does nothing 

 to explain it. 



In his recent important work on the Foraminifera, 

 Mr. E. Heron-Allen has directed attention to the pur- 

 poseful behaviour shown by many of these Protozoa 

 in the selection and arrangement of foreign materials 

 worked into their tests. He sums up the evidence on 

 this subject in a paper in the Journ, R. Microsc. Soc, 

 vol. xvi., part 6, and concludes "that there appears to 

 be no organism in the animal kingdom, however 

 simple be its structure, which lives a life of its own 

 independently of any other organism, which is not 

 capable of developing functions and behaviour . . . 

 which in the Metazoa might be called, and would 

 properly be so called, Phenomena of Purpose and In- 

 telligence." 



Turning from protozoa to insects, Mr. F. M. How- 

 lett publishes (Bull. Entom. Research, vi., part 3, 

 19 15) some puzzling observations on the chemical re- 

 actions of fruit-flies. In the genus Dacus, the males 

 and not the females of certain species are strongly 

 attracted by different eugenol-compounds, the smell of 

 which resembles that emitted by plants that also 

 attract the male flies. The corresponding- females do 

 not apparently emit similar odours, nor were they 

 seen to frequent the odoriferous plants. Of the pos- 

 sible explanations suggested by Mr. Howlett, the most 

 probable therefore seems to be that the smells are 

 characteristic of some food which is attractive to males 

 only. 



STUDIES IN MENDELISM. 



AN important paper on the inheritance of the 

 flowering time in peas and rice, by Yuzo 

 Hoshino, has been published in the Journal of the 

 College of Agriculture (Imp. Univ. Sapporo, Japan, 

 vol. vi., part ix.). The author concludes that in peas 

 the inheritance is governed by two pairs of Mendelian 

 factors. In the one pair are lateness (dominant) and 

 earliness (recessive) ; in the other pair are acceleration 

 (dominant, hypostatic to lateness) and retardation (re- 

 cessive, hypostatic to earliness). Gametic coupling 

 between flowering time and flowering colour is also 

 indicated, early red and late white flowers being equal 

 in number and far fewer than early whites or late 

 reds. The experiments on rice were not conclusive, 

 but the author suggests that three pairs of Mendelian 

 factors are probably concerned. 



In the Proc. Amer. Phil. Soc. (vol. liv.. No. 218) 

 Bradley M. Davis discusses from the Mendelian point 

 of view the mutation phenomena in CEnothera, and 

 advises caution in accepting results based on breeding 

 experiments where there is reasonable doubt as to 

 the gametic purity of the parent " species." 



The March number of the Journal of Genetics 

 (vol. v., No. 3) contains several papers of interest. 

 Misses C. Pellew and F. M. Durham find that from 

 reciprocal crosses between Primula verticiUata and 

 P. floribunda plants resembling the female parent are 

 generally obtained, these breeding true to type when 

 self-fertilised. Occasionally the hybrids are of the 

 P. Kewensis form, some partially sterile and others 

 fertile. J. V. Eyre and G. Smith discuss some results 

 from the cross-pollination of varieties of flax. W. 

 Neilson Jones and Dr. M. Chevely Rayner contribute 

 some important results from breeding experiments 

 with two varieties of Bryonia dioica. The presence of 

 waxy bloom on the ripe berry is a recessive character; 

 the capacity to increase the number of vascular bundles 



NO. 2431, VOL. 97] 



in the stem beyond ten " behaves as a simple dominant 

 to the absence of such capacity." The authors con- 

 sider that their experiments "emphasise the need for 

 caution in the subdivision of existing species without 

 recourse to breeding tests." A supplement to Dr. L. 

 Doncaster's well-known researches on the magpie 

 moth {Abraxas grossulariata) is afforded by the Rev. 

 J. M. Woodlock, who discovered near Dublin a new 

 variety of the moth, resembling lacticolor in pattern, 

 but behaving as a simple recessive to typical grossu- 

 lariata without any sex-limiting complication. The 

 typical grossulariata pattern depends, according to 

 Father Woodlock, on two dominant characters; the 

 absence of one results in the appearance of lacticolor, 

 that of the other in the appearance of the new variety, 

 which the reverend, author — ^perhaps with some re- 

 miniscence of literary criticism — proposes to designate 

 as "O." 



EFFECT OF TEMPERATURE ON SOILS. 



THE effect of temperature on some of the most 

 important physical processes in soils has been 

 studied experimentally by Mr. George J. Bouyoucos, 

 of Michigan Agricultural Experiment Station, and his 

 results are published as Technical Bulletin No. 22. 

 Very few problems of this kind have been worked out 

 experimentally. Our knowledge is based almost en- 

 tirely on deductions from the laws of surface tension, 

 viscosity, and expansion as affected by temperature. 

 It is not surprising that when put to the test of ex- 

 periment, under the complicated conditions that obtain 

 in soils, these deductions are found wanting. When 

 one-half of a column of soil of uniform moisture con- 

 tent is kept at 20° or 40° C, and the other at 0° C, for 

 eight hours, the percentage of water transferred from 

 the warm to the cold soil increases in all types of 

 soil with rise of moisture content until a certain water 

 content is reached and then falls. The author terms 

 the percentage of moisture at which this maximum 

 transfer occurs, the thermal critical moisture content. 

 The laws of capillarity and viscosity do not by them- 

 selves explain this result. Experiments on the move- 

 ment of water vapour from warm to cold soil through 

 an air space showed that such movement was insignifi- 

 cant under all conditions tested. The conclusion is 

 drawn that the source of water as dew is not derived 

 from the soil vapour, as commonly believed. 



The translocation of water from a moist soil at 

 0° C. to a dry soil at 40° C. is very small. This has 

 a most important bearing on the preservation of soil 

 moisture by mulches. The study of the effect of tem- 

 perature on the rate of percolation of water in soils 

 showed that the rate of flow increases uniformly with 

 rise of temperature only in the case of sand. In other 

 soils, the rate of flow increases up to about 30°, and 

 then falls. It is suggested that in the latter soils the 

 swelling of colloidal matter closes the channels through 

 which the water flowed. Although other reasons 

 might be put forward to explain this effect, the 

 author's hypothesis agrees with some of the known 

 properties of colloids. Further, when the soil was 

 tested at 20° C, then at 50° C, and again at 20° C, 

 the two readings at 20° C. were not the same. This 

 hysteresis effect is interesting. 



The last section of the paper is devoted to the rela- 

 tion of temperature to soil aeration. The rate of flow 

 of air through soil decreases with rise of temperature, 

 and this effect is most marked in soils likelv to contain 

 colloidal matter, e.g. clays and peat. Although the 

 author is, perhaps, rather too ready to assume that the 

 views commonly held on many of the points arising 

 from his^ work are inconsistent with his own deduc- 

 tions, this bulletin is a notable contribution to our 

 knowledge of the dynamics of soils. 



