1919] AGKICULTUEAL, BOTANY. 223 



The results have not yet been sulliciently assembled to warrant definite con- 

 clusions. Tlie most outstanding fact is the rapidity with wliich the surface 

 temperature of a leaf growing in the open may fluctuate within a time of 20 

 to 60 seconds, often amounting to from 1 to 3° C, and in moderately strong 

 winds changing as much as 5° in 30 seconds. 



Evolution by hybridization, E. C. Jeffrey {Brooklyn, Bot. Gard. Mem., 1 

 {1918), pp. 208-305, pi. 1).. — This is a critical review of recent publications. 



Inheritance studies on castor beans, O. E. White {Brooklyn Bot. Gard. 

 Mem., 1 {1918), pp. 513-521, pis. 6). — Hybridization studies involving several 

 thousand plants have been pursued through the Fi, F2, and in some cases, th.> 

 F3 generations derived from 50 or more types grown from seeds representing 

 dirt'ereut growers. Very little cross-fertilization occurred. Details are given, 

 \\ ith some interpretation of the data obtained, from the study on stem color, 

 bluoni, dehiscent and indehiscent pods, and seed coat color. 



The inheritance of doubleuess in Chelidoniuni majus, K. Sax {Genetics, 

 3 {1918), No. 3, pp. 300-307).— Presenting results of statistical studies of the 

 relation of petals and stamens and of the inheritance of doubleuess in C. 

 majus, the author states that this quality appears to be a simple recessive 

 character. There is apparently a continuous series in degree of doubling 

 from singles to full doubles in the F2. Much greater variation is noted in 

 the doubles, which are recessive, than in the singles of which two-thirds are 

 heterozygous. The F2 doubles are no more variable than individual double 

 plants of that generation. A high degree of negative correlation exists be- 

 tween petal numlier and stamen number in the F2, due to petalody. 



Duplication and cohesion in the main axis in Cichorium intybus, A. B. 

 Stout {Brooklyn Bot. Gard. Mem., 1 {1918), pp. 480-JiS5, pi. 1, fig. i).— The 

 terms duplication and cohesion are here used to designate a very special 

 typo of fasciation, observed by the author to occur in a cultivated variety 

 of chicory and made the subject of a study, the results of which are reported 

 herein. In addition to a very decided duplication with cohesion of the main 

 axis, other irregularities occur in the development of cotyledons and plumule, 

 Involving in some cases fusion or suppression. 



The character of duplication and cohesion of the main axis is strongly 

 but not completely heritable. In an Fi hybrid generation of crosses be- 

 tween plants showng duplication and plants of wild stock free from these 

 abnormalities, the duplication is incompletely dominant both as to degree of 

 expression and number of plants affected. An intermediate type is noted in 

 which the only indication of duplication is seen in a mixed and irregular 

 phyllotaxy. 



Intercrosses between self-sterile plants, E., M. East {Brooklyn Bot. Gard. 

 Mem., 1 {1918), pp. l-'f 1-^153). — Work done with Nlcotiana forgetiana and 

 7^. aluta and their intercrosses, part of the data from which have been pub- 

 lished elsewhere (E. S. R., 38, p. 823), is considered to show unmistakably 

 tliat the behavior of self -sterile plants in intercrosses is governed by a rela- 

 tively small number of factors, which act through the pollen; also that the 

 gametes of plants having like constitutions as regards effective factors are 

 incompatible in the sense that they do not make a normal pollen tube growth 

 and hence do not reach the ovary in time for fusion to occur. 



This interpretation is considered to show A-ihy plants are both self-sterile 

 and cross-sterile. It accords completely with the fact that a population of 

 plants may be divided into groups on the basis of their mating proclivities, 

 and that each member of any group is cross-sterile with every other individ- 

 ual of that group although fertile with every individual of every other group. 



