486 BOTANICAL GAZETTE [December 



Absorption limits. — The conditions existing in roots while in equilibrium 

 concentration (equal absorption and leaching of ions) with the surrounding solu- 

 tion have been studied by Harvey and True"" in sweet corn, squash, peanut, 

 and soy bean. The value of the equiUbrium concentration was found to be 

 specific for each plant. Thus for sweet corn it was 12—15 NX lo"^, while for 

 squash it was 35-40 NXio~^, and for the peanut 50 NXio"'^. It was inde- 

 pendent, however, of the kind of electrolyte used, or of the original concen- 

 tration or volume used, provided the original concentration was non-toxic, 

 and that the volume contained less salt than the plant requires for full growth, 

 so that minimum limits for absorption would be reached. The electrolyte 

 content of the solution after equilibrium has been reached is determined partly 

 by volatile ions (CO2) which are quantitatively equal for all plants grown under 

 equal conditions if equilibrium with the atmosphere has been established; but 

 it is mainly determined by the rate at which ion-producing compounds of the 

 cell break down, and the rate of reabsorption of these ions. The behavior of 

 roots at minimum concentrations seems to substantiate Stiles' view that there 

 are concentration limits below which the root cannot absorb enough salts, 

 merely because the nutrient solution is too dilute. — C. A. Shull. 



Embryogeny in angiosperms. — Soueges,'s in continuing his studies of 

 embryogeny in angiosperms, has emphasized his claim that the laws which 

 govern development are the same in monocotyledons and dicotyledons. 

 The investigations cited compare typical representatives of monocotyledons 

 and dicotyledons {Anthericum and Polygonum). According to this investi- 

 gator the only difference in the embryogeny of the two groups is that in 

 dicotyledons the laws are applicable at the first division of the egg; while in 

 monocotyledons these are not applicable untU the second division, the apical 

 cell of the 2-ceUed embryo being the equivalent of the egg-cell in dicotyledons. 

 It is claimed that the variable behavior of the basal cell of the proembryo of 

 monocotyledons accounts for the differences that have been observed. This 

 thesis is illustrated in detail in the development of the different regions of the 

 embryo. 



It is becoming increasingly evident that embryogeny in angiosperms is 

 not represented by two sharply contrasted methods, and these detailed results 

 of Soueges confirm other work dealing only with the cotyledon situation. 

 —J. M. C. 



■■' Harvey, R. B., and True, R. H., Root absorption from solutions at min- 

 imum concentrations. Amer. Jour. Bot. 5:516-521. 1918. 



■5 Soueges, R., Embryogenie des Liliacees. Developpement de I'embryon 

 chez r Anthericum ramosum. Compt. Rend. pp. 4. July 1918. 



, Embryogenie des Polygonacees. Developpement de I'embryon chez le 



Polygonum Persicaria. Compt. Rend. pp. 3. April 1919. 



