: 
Yeap e 
1903] CURRENT LITERATURE 473 
100 to g2 in the almost homogeneous mesophyll of the bamboo leaf.—H. C. 
COWLES 
THE EMBRYO-SAC of two sterile hybridsis discussed in a recent paper by 
Tischler.” The hybrids are Rzbes Gordonianum Lem. (R. aureum X sanguin- 
eum)and Syringa chinensis (S. vulgaris x persica). Both parents of 2. Gor- 
donianum have normal embryo sacs with conspicuous nutritive tissue in the 
chalazal region of the ovule. In the hybrid this nutritive tissue is lacking and the 
development of the embryo sac is usually checked long before it reaches the 
fertilization period, the megaspores often failing to germinate at all. 
In the parents of Syringa chinensis the nutritive tissue is in the form of a 
jacket derived from the integument and surrounding the embryo sac, which 
in both cases is normally developed. In the hybrid the nutritive jacket is 
more highly developed than in the parents, but the embryo sac becomes dis- 
organized quite early, so that the stage at which fertilization might occur is 
seldom or never reached. 
References are given to the few cases previously described of irregularities 
and imperfections in the development of the ovules and embryo sacs of 
sterile hybrids.—C, J. CHAMBERLAIN. 
P. D. Buck * has made a comprehensive study of the stomata and aera- 
tion tissues of a large number of Swiss plants, especially those of beech 
woods. A number of modifications of Schwendener’s types are described, 
together with a new type, that of Ramunculus acer. Buck describes a num- 
ber of variations on the same individual, especially differences in the level of 
the guard cells, While some groups, such as conifers, sedges, and grasses, 
are characterized by a definite structural type, it is more common to fin 
rather a relation to the form of the leaf, or to the habitat, Perhaps his most 
interesting contribution deals with subterranean stomata, of which he finds 
three types: functional, functionless, and latent. The latent stomata attain 
full development only when the shoot which bears them comes above the 
_ Surface. For the functional subterranean stomata, Mohl's theory as to the 
mechanism, of course, cannot be held, as there is no chlorophyll or synthetic 
activity, though starch is present. They were found to open and close like 
ordinary stomata when the moisture content of the air was changed. 
last section of the paper deals with the spongy parenchyma, of which sacae 
types are noted.—H. C. CowLes. 
THE U. S. Bureau of Soils ina recent bulletin” presents a comprehensive 
Study of the influence of soil chemistry upon crop production. It is shown 
7 TISCHLER, G., Ueber Embryosack-obliteration bei Bastardpflanzen. Beih. Bot. 
Centralbl. 15 : 408-420. /. 5 
Buck, P. D. Beitrige zur vergleichenden Anatomie des Durchliiftungssystems. 
Inaugural Dissertation. Freiburg i. d. Schw. 1902. pp. 93. 
*9 WHITNEY MILTON, and CAMERON, F. K., The chemistry of the soil as related 
to crop production. Bull. 22, Bureau of Soils. U.S. Dept. of Agric. pp. 71. 1903. 
