124 PHYSIOLOGY [Bot. Absts., Vol. VI, 



barley were conducted as follows: Grains were soaked in water; after 3 hours 5 embryos were 

 isolated and placed on blotting paper wet with nutrient solution (lot Pi) ; one day later ,5 more 

 were similarly treated (lot P 2 ) the next day 5 more were similarly treated (lot P 3 ). In P 2 the 

 growth of the embryo had begun; in P 3 and in checks (embryos not separated from endosperm) 

 the plumule had become green, but the endosperm had decreased only slightly in weight. On 

 the third day measurements and weighings showed that the plumule and first adventitious 

 root were nearly twice as long in P 3 and Pi, and that P 2 had gained from 2\ (barley) to 6? 

 (wheat) times as much weight as had Pi. On the seventh and twentieth days all lots were 

 growing, but checks and P 3 were much better developed than Pi and Pi. From this and sev- 

 eral other experiments it is concluded that in no case is endosperm indispensable to the devel- 

 opment of the plantlet; all species treated can grow in nutrient solution. The removal of 

 the endosperm retards the life processes of the embryo; its presence favors the development of 

 the plantlet during the first few days and results in marked changes later. However, since 

 the amount of endosperm material consumed by the third day is so slight this effect must be 

 due to some stimulus exciting enzymatic activity and the use of reserve materials within the 

 embryo itself. — Plants of all lots were raised to maturity in soil. Although plants of lot Pt 

 were often nearly as well developed as the checks, those of lots Pi and P 2 showed more pro- 

 nounced modifications: roots less branched; stems simpler; leaves smaller, less numerous and 

 simpler in form; inflorescence precocious, less well developed and showing various abnormali- 

 ties; fruits often aborted; all parts dwarfed. — A comparison of sections of Pi plants and the 

 checks in Ricinus, Nigella, Papaver, Solanum, Torilis, and Zea, showed the internal structure 

 to be much simpler in the plant which had been deprived of their endosperm. In the stem 

 the cells are fewer and smaller; the cortex shows fewer layers; the tissues of the central cyl- 

 inder are less differentiated, the vascular bundles being fewer and with fewer elements; the 

 pith is relatively large. Similar modifications are present in root and petiole. In the leaf 

 the epidermis appears nearly normal, but the other tissues show reduction in the number and 

 size of their elements. The greater the dwarfing the more pronounced are these modifications. 

 — L. W. Sharp. 



REGENERATION 



867. Loeb, J. Quantitative laws in regeneration. I. Jour. Gen. Physiol. 2: 297-307. 

 1920. — Dry weight measurements show that, when a piece of stem of Bryophyllum calycinum 

 inhibits the production of shoots and roots in an attached leaf, the stem gains in weight and 

 this gain approximately equals the mass of shoots and roots that the leaf would have produced 

 if it had been detached from the stem. "This suggests that the inhibitory influence of the 

 stem upon the formation of shoots and roots in the leaf is due to the fact that the material 

 available for the process naturally flows into the stem." — Otis F. Curtis. 



868. Okada, Yoonosuke. Studien iiber der Proliferation der Markholenzellen im Stengel 

 der Vicia faba. [Studies on the proliferation of pith cells in the stem of Vicia faba.l Bot. Mag. 

 Tokyo 34: 19-34. 4 photog., 7 fig. 1920. — This paper gives a brief review of the literature and 

 describes the author's methods and results. The hollow stems were injected by means of a 

 glass hypodermic syringe with distilled water and various dilute salt solutions, sugar, glycer- 

 ine, alcohol, and ammonia in different concentrations and at different temperatures. Temper- 

 ature had little effect and dilute solutions differed little or not at all from water. More con- 

 centrated solutions failed uniformly to produce any proliferation. The author concludes that 

 water absorption and increased turgor are the chief causes of the hypertrophy and the division 

 of the pith cells. From one to seven injections were made in each stem, resulting in intumes- 

 cences in the majority of cases. The entire cavity was sometimes filled. Acids and a sub- 

 stance turning orange red with H 2 2 accumulated in the affected cells. — Leonas L.Burlingame. 



TEMPERATURE RELATIONS 



869. Bigelow, W. D., and J. R. Esty. The thermal death point in relation to time of some 

 resistant organisms. [Abstract.] Absts. Bact. 4: 10. 1920. 



