1919] AGRICULTURAL BOTANY. 727 



No. 3, pp. 70-90, pis. 2, figs. 2) . — Summarizing experimental and other evidence 

 as presented, tlie author states that of the four potential megaspores in maize 

 only one persists and becomes functional. The embryo sac is a modified form 

 of the ordinary 7-celled type. The antipodals undergo division. Tlie sperms 

 are matured inside the pollen grain. Although external conditions and length 

 of tlie silk determine the time required for the growth of the pollen tube, 

 fecundation has occurred about 24 hours after pollination. The work of 

 Guignard on double fecundation (E. S. R., 13, p. 620) is conidered as verified 

 by these observations. A triple fusion occurs almost simultaneously with 

 fecundation of the egg, but the endosperm develops much more rapidly than 

 does the embi'yo. The assumption that the endosperm is sporophytic is con- 

 sidered sound. The cytological data substantiate practically all the assump- 

 tions of cytological fact upon which recent experiments on endosperm heredity 

 in maize have been based. 



The ancestry of maize, J. H. Kempton (Jour. Wash. Acad. Sci., 9 {1919), 

 No. 1, pp. 3-11). — This is mainly a discussion of a contribution by Weatherwas 

 (E. S. R., 40, p. 728). 



Hybrid perennial sunflowers, T. D. A. Cockeeell {Bot. Oaz., 67 {1919), No. 

 3, pp. 264-266). — It is stated that near Boulder, Colo., where Helianthus 

 orgyalis and H. maximiliani have been growing in close proximity for a num- 

 ber of years, a distinct form has appeared which is on the whole intermediate 

 between these two, and which is supposed to be a hybrid resulting from their 

 intercrossing. In order to bring out clearly the features of the new plant, each 

 character is described in connection with a corresponding character of each 

 supposed parent, 



Chondriosomes in plants, C. J. Chamberlain {Bot. Gaz., 67 {1919), No. 5, pp. 

 270, 271 ) . — This is a summary of results reported by investigators in the study 

 of chondriosomes, chiefly in plants, the name (of the many mentioned which 

 have been proposed for structures of this order) being favored on account of 

 its noncommittal character. Attention is called to the bibliographies given in 

 reports of studies on such bodies, that by Cavers (E. S. R., 33, p. 631) cover- 

 ing the literature of the subject up to 1914, and that by Mottier (E. S. R,, 

 39, p. 332) bringing it up to 1918, 



It is considered to have been established that chondriosomes are not arti- 

 facts, that they multiply by division, and that some of them give rise to plastids. 

 Their part in heredity, however (if they have any), remains to be demonstrated. 



The physiological basis of morpholog-ical polarity in regeneration, I, J. 

 LoEB {Jour. Gen. Physiol, 1 {1919), No. 3, pp. 337-362. flr/s. ^8).— Continuing 

 previous reports (E. S. R., 41, p. 526) the author presents qualitative evidence 

 regarding the inhibitory effect of a leaf upon shoot formation, discussion of 

 more quantitative experiments being reserved for a later paper. 



In Bnjophylhim calycinum, growth of two apical leaves suppresses shoot for- 

 mation in all dormant buds situated lower down the shoot, that of one apical 

 leaf influencing the lower buds on that side (half) of the stem. Removal of 

 one-half of the petiole of a leaf permits growth of lower buds in the correspond- 

 ing quadrant of the stem. This inhibitory influence of the leaf diminishes or 

 disappears when the mass of the leaf is reduced below a certain limit. The 

 inhibitory influence of an apical leaf in case of horizontal suspended stems is 

 greater when the leaf is on the upper side of the stem. The facts observed 

 are considered to justify the suggestion that the inhibitory influence of the leaf 

 upon shoot formations is due to inhibitory substances secreted by the leaf and 

 carried with the sap toward the base of the stem. An apical leaf accelerates 

 root formation in the basal part of the stem in proportion to the mass of the 

 leaf. 



