1910] CURRENT LITERATURE 305 
to those that are sufficiently humid to permit the development of luxuriant 
mesophytic forests. GRoom’s paper is most suggestive, and adds considerably 
to our knowledge concerning the difficult problem of coniferous xerophytism.— 
Henry C. Cow Les 
. Nutrition of the embryo in Labiatae.—Bii1incs® has investigated the 
nutritive mechanism associated with the embryo sac of certain Labiatae, 
a subject that deserves more attention from morphologists. The ordinary sac 
which is oval or elliptical in longitudinal section, and which encroaches uni- 
formly upon the surrounding tissues, has come to be regarded as the more 
or less fixed “type” of sieossites tian sac. game the Sympetalae especially, 
however, a much mor has begun to be uncovered, 
including special digestive layers and special absorptive regions of the sac, _ 
latter usually taking the expression of tubular haustorial extensions. BILLIN 
investigated 15 species of Labiatae, representing 14 of the most cucu ate 
genera. The results were uniform enough and differed enough from other 
the Labiatae lack the special digestive layer. There are three features com- 
mon to the species studied, and possibly to the whole family, to which the 
author calls attention: the micropylar haustorium (more or less extensively 
developed), the much-elongated suspensor, and the antipodal canal or process. 
alvia is an exception to this statement, for it has a short suspensor and no 
micropylar haustorium; and the two species investigated “are unique in 
Ving two haustorial outgrowths, one coenocytic and one composed of ordi- 
hary endosperm tissue’’ (these haustoria are in addition to the well developed 
antipodal canal). The author thinks that such variations from the general 
Conditions as are shown by Salvia “suggest a taxonomic rearrangement.”— 
M.-C. : 
Correlation in oats.—WALDRON®° has compared the height of culm, length 
of head, number of grains per head, and average weight of grains in a variety 
e of oats growing at Dickinson, North Dakota. The examination of 1000 
- Plants discovered decided negative correlations (—o.595+0.013, —O.51I1* 
9.015, and —o.404+0.017) between the weight of grains and number of 
Stains per head, weight of grains and length of head, and between weight of 
- ‘gtains and Lnigth of culm. He reaches the conclusion that in selecting the 
_ heaviest grains in this variety, the breeder selects plants somewhat below the 
age 
* Brtuncs, F. H., The nutrition of the embryo sac and embryo in certain 
Labiatae. eis Univ. Bull. 5:67-83. pls. 11-14. 1909. 
7° Watpron, L. R., A suggestion regarding heavy and light seed-grain. Amer. 
ica 44:48-56. 1910. 
