224 SCIENCE PROGRESS 



LACROIX, A., L'ankaratrite a facies lamprophyrique de Sainte-Florine, pres 



Brassac (Haute Loire), Ibid. 62-71. 

 LACROIX, A., La composition chimique du gabbro du Pallet (Loire Inferieure), et 



ses varietes endomorphes (diorites hypersthe"niques a cordi^rite) et des roches 



filoniennes qui l'accompagnent, Ibid. 74-9. 

 BUCHER, W. H., On Ripples and Related Sedimentary Surface Forms, and their 



Palaeogeographic Interpretation, Amer. Journ. Set. 1919, 47, 149-210; 



241-69. 

 Kindle, E. M., Separation of Salt from Saline Water and Mud, Bull. Geol. Soc. 



Amer. 1918, 29, 471-88. 

 Tarr, W. A., Rhythmic Banding of Manganese Dioxide in Rhyolite Tuff, Journ. 



Geol. 191 8, 26, 610-17. 



BOTANY. By E. J. Salisbury, D.Sc, F.L.S., University College, London. 



Genetics. — Variation as exhibited by the vegetatively-produced 

 offspring of Lemna minor has been studied in an extensive series 

 of cultures by N. B. Mendiola (Genetics, March). The range of 

 area of the frond in 200 wild individuals which had attained 

 maturity was from 2-26-6-4$ sq. mm., with 4-019 ± -037 as the 

 mean. Variation was found to occur both as to the shape of 

 the fronds and their speed of formation ; a variation that was 

 most marked under conditions favourable to growth. Races 

 were isolated from the wild population which differed in these 

 respects, and thus supported the view that pure lines were 

 involved. 



Sex segregation in the Bryophyta (Jour, of Genetics) is the 

 subject of a paper by Collins, who reviews briefly the work 

 of El. and Em. Marchal. These authors found that the 

 spores of dioecious forms were unisexual, the two sexes being 

 produced in approximately equal numbers. Protonemata 

 produced from the vegetative axes were of the same sex as the 

 plant from which they were derived, but those from the 

 sporophytic tissue produced a low proportion of hermaphrodite 

 axes. 



Collins, in his experiments, has produced protonemata from 

 antheridia, from perigonial leaves, and from spores. The last- 

 named produced sporogonia, but the two former were entirely 

 male. The author suggests a somatic segregation in the hap- 

 loid tissue as a possible explanation. 



In the same journal, Bateson and Sutton describe inheri- 

 tance experiments on Begonia in relation to doubleness and 

 sex. Single was found to be dominant, but the proportion of 

 doubles in F, exhibited great fluctuation. A wild single species, 



