lOO BOTANICAL GAZETTE [jaxuary 



Another very interesting fact brought out by the author's work on sweet 

 potatoes is the apparent stabiUty of cane sugar in relation to the respiratory 

 processes in these roots, as cane sugar does not seem to be consumed by either 

 anaerobic or normal respiration. — Charles O. Applemax. 



Analysis of quantitative variation. — Brotherton and Bartlett" have 

 presented the results of a very significant piece of research. The investigation 

 as it stands belongs to the field of plant physiology, but probably it is most 

 significant in the bearing upon certain problems of genetics. Plants of Phase- 

 oltis midtiflorus grown in hght and darkness were compared as to length and 

 number of epidermal "cells of a given internode. For the physiologist the 

 results may be summarized in the following statement: "The effect of hght is 

 that it retards extension of the cells, and that as an indirect result there are 

 fewer secondary di\dsions, since relatively fewer primary cells enter the range 

 of length within which division takes place." For the geneticist we quote the 

 following: "The mathematical formulation of the results of size inheritance 

 according to the multiple factor hypothesis should be paralleled by a biological 

 analysis, the object of which is the identification of the several factors con- 

 cerned." Thus size differences may be resolved into number or size of con- 

 stituent cells or both. "In the investigation of quantitative variations of a 

 hereditary nature it seems Ukely that the study by the histological method of 

 reactions to the en\aronment and of the obscure reaction known as 'vigor of 

 heterozygosis' will afford a means of correcting for these disturbing factors." 

 It is probably true that heritable size differences express themselves directly 

 in the cells of tissues deeper than the epidermis, and that the change in the 

 epidermis amounts merely to a mechanical response to these forces within. 

 It would probably be advisable, therefore, to carry the analysis to more sig- 

 nificant tissues. — Merle C. Coulter. 



Root growth in cuttings. — Curtis'^ has published an important contribu- 

 tion to the physiology of root formation in cuttings. A number of forms were 

 used, but Ligustrum ovaliJoUum furnished most of the experimental material. 

 Nutrient solutions of the strengths used in culture work with seedlings were 

 found to be distinctly injurious to woody cuttings. Treatments with potas- 

 sium permanganate resulted in a xexy marked increase in root growth of various 

 woody cuttings. After discussing several possible explanations for this stimula- 

 tion, the author concludes that it is most probable that the potassium per- 

 manganate increases respiratory activity by catalytically hastening oxidation. 

 It is known that when potassium permanganate comes in contact with organic 

 matter manganese dioxide is precipitated and oxygen is liberated. There was 



" Brotherton, Wilber, and B.artlett, H. H., Cell measurement as an aid in 

 the analysis of quantitative variation. Amer. Jour. Hot. 5:192-206. 1918. 



'3 CtJRTis, Otis F., Stimulation of root growth in cuttings by treatment with 

 chemical compounds. Cornell Univ. Agric. Exper. Sta. ^Memoir 14:71-138. 1918. 



