526 EXPERIMENT STATION RECORD. {Vol.37 



It is consiflcred as an important feature of both spear leaves and spear 

 shoots (in whicli the leaves are rolled parallel to the midrib) that the unfold- 

 ing begins at the apex and travels downward, the tip of the leaf or shoot thus 

 developing an increased periphery on reaching the light, while the part below 

 remains small, thus greatly reducing resistance to the emergence of the remain- 

 ing part of the shoot or leaf. The third (and in some respects more elaborate) 

 type, in which the stem or petiole emerges in a bent condition, is dealt with in 

 some detail. It is stated that the straightening of the bent organs h a growth 

 phenomenon which normally takes place under the stimulus of light at a rate 

 corresponding somewhat to its intensity, but sometimes occurring eventually in 

 darkness. 



Linkag'e in maize: Aleurone and chloropliyll factors, E. W. Lindstrom 

 {Amer. Nat., 51 {1917), No. GO-',, pp 225-2 J7" ) .—The author states that linkage 

 between R, one of the aleurone factors (of which there are said to be 5 pairs), 

 and G, one of the chlorophyll factors (of which the author has found that there 

 are at least 7 pairs), shows approximately 20 per cent cros.sovers, the crossing 

 over occurring in both male and female gametogenesis of the monoecious maize 

 plant. Preliminary tests indicate that G is also linked with L, a seedling 

 chlorophyll factor, the factor pairs Rr, Gg, and LI constituting one factorial 

 group in maize. 



The different meanings of the term " factor " as affecting clearness in 

 genetic discussion, H. B. Frost {Amcr. Nat., 51 (1917), No. GO-i, pp. 24-i-250).— 

 The author proiioses to employ in genetic discussion the two distinct meanings 

 now in iise for the term factor, so that a genetic (Mendelian) factor will mean, 

 in one sen.'je, a property or characteristic of the germ plasm, more or less con- 

 veniently delimited for the analysis of segregating heredity; in tlie other, an 

 actual material unit of genetic segregation, of unknown nature, but probably 

 a geneticaVly indivisible portion of a chromosome in a particular state. The 

 presence-and-absence scheme employs properly the first only of these meanings; 

 the Morgan-Castle scheme may use either. 



Notes on the flora of Sitka, Alaska, J. P. Anderson (Proc. Iowa Acad. Set., 

 23 {1916), pp. Ji27-JiS2, figs. 16). — The author, presenting the re.sults of col- 

 lections, observations, and research of two years near Sitka, states that in the 

 area in question the Canadian, Hudsonian, and Arctic-Alpine zones are repre- 

 sented. The plants segregate into five or six typical habitats, which are syste- 

 matically discussed, as are economic plants including forest, fruit bearing, and 

 other species. A number of fungi are listed with their hosts. The collections 

 made are to be added to those at the Alaska Sitka Experiment Station. 



An account of the chief types of vegetation in South Africa, with notes 

 on the plant succession, J. W. Bews (Jour. Ecnlngii, J^ (1916), No. S-4, pp. 129- 

 159, fig. 1). — Giving a somewhat extended, though confessedly incomplete, 

 account of the vegetation prevalent in portions of South Africa as related to 

 various factors, the author states that the typos of vegetation found there are 

 very varied, showing many stnges and tendencies as regards order of succession. 

 One striking feature is the rarity of formations or associations dominate<l by a 

 single species. In some cases, but not all. this may be considered to indicate a 

 lack of stability in the environmental conditions. 



Experiments on the effects of constituents of solid snielter wastes on 

 barley grov/th in pot cultures, C. B. Lipman and W. F. Gericke (Univ. Col. 

 Pubs. Agr. Set., 1 (1917), No. 13, pp. 495-5S7). — Following some preliminary 

 Investigations by Lipman and Wilson previously noted (E. S. R., 30. p. 130), 

 the present authors institued in 1912 new and more complete experiments to 

 ascertain whether sulphates of such metals as copper, zinc, lead, iron, and 

 manganese in i^oil are toxic to barley; whether these substances are toxic in the 



