1918] CURRENT LITERATURE 543 
prove a profitable crop. Some typical average annual increments are Carya 
ovata 0.22 inch, Quercus macrocarpa 0.30 inch, Q. velutina 0.29 inch, Acer 
saccharinum o.63 inch, and Juglans nigra 0.34 inch—Gero. D. FULLER. 
Inheritance of height in peas.—According to MENDEL’s original classic 
experiment with peas, the cross tall dwarf gives a simple monohybrid ratio, 
with tallness dominant. The work of a number of recent investigators, how- 
ever, has indicated that height in peas is a much more complex character, and 
that Mendel’s 3:1 ratio by no means states the whole truth. Wutre” has made 
a critical examination of these investigations and has added some of his own. 
He concludes that there are at least 5 genetic factors involved, 2 for internode 
length, and 3 for number of nodes. He points out, however, that the same 
genetic pea material that MENDEL used will still give the 3:1 ratio. ‘The 
inheritance of height in peas has become complex only because of studies on 
new or distinctly different material, the characters of which, there is reason 
to believe, are due to distinct mutations.”—MERLE C. CouLTER. 
Intercellular canals—ReEcorpD® has investigated the occurrence of inter- 
cellular canals in dicotyledonous woods, and has discovered 16 families in 
which they occur, mostly tropical. In some cases they are a normal feature 
of the wood, while in other cases they develop as a result of injury. They 
vary in direction and origin, in certain features resembling those of gymno- 
sperms, but in many important features quite distinct. The secretions 
exhibit a wide range of variation, being resinous, oily, gummy, or tanniferous, 
as contrasted with conifers, in which the secretions are wholly resinous. 
ReEcorD concludes that the presence of intercellular canals in wood is a valu- 
able diagnostic feature, and it was with this primarily in view that the investi- 
gation was made.—J. M. 
Inheritance in Pisum.— WHITE” has presented a very significant paper on 
the interrelation of the genetic factors of Pisum. He has collected a mass of 
data of his own and also of earlier investigators of Pisum. He distinguishes 
35 factors and discusses 5 linkage groups. A model section appears under 
the title “Modification of the expression of Pisum factors by different environ- 
ments and by each other.” This is one of the first successful attempts to make 
an intensive study of inheritance in plants, such as has been so well made on 
the fruit fly. Another such study, on corn, is now maturing at Cornell under 
the direction of Dr. R. A. EMERSON.—MERLE C, COULTER. 
"7 Waite, Ortanp E., Inheritance studies in Pisum. UI. The inheritance of 
height in peas. Mem. Torr. Bot. Club 17:316-322. fig. r. 1918. 
8 RecorD, S. J., Intercellular canals in dicotyledonous woods. Jour. Forestry 
as: —_ 1918. 
9 Waite, ORLAND E., Inheritance studies in Pisum. IV. Interrelation of the — 
tase factors of Pisum. doen Agric. Research 11:167-190. 1917. 
