AGRICULTURAL BOTANY. 829 



On well-marked aerotropic growths of Bacillus megatherium, J. C. John- 

 son (Ann. Bot.. [London], 26 (1912), No. 103, pi). 9-'f9, 950).— The author re- 

 ports on his observations made for 3 years with the annual periodicity of 

 growths of this bacterium on the dead extremities of the I'oots of a palm. The 

 growths are still being watched for any gradual change from the flat films to 

 the raised growths observed, in the hops of showing a connection between ordi- 

 nary free-living bacteria and the more highly specialized fructifications of the 

 Myxobacteriacefe. 



Spiraea ulmaria and its bearing on the problem of xeromorphy in marsh 

 plants, I{. H. Yapp (Ann. Bot. [London], 26 (1912), Yo. 103, pp. 815-870. pis. 

 3, figs. 11). — This is a study of the xerophytic characters exhibited by meadow 

 sweet, reviewing also the present state of laiowledge in regard to swamp 

 xerophytes, and leading to the following general conclusions : 



Xeromori)hy is of physiological utility to those bog and marsh plants which 

 exhibit such characters, these being directly related to the needs imposed upon 

 the plant by the special nature of its habitat. In each case, howevei', the 

 special regulatory devices are required to meet not so much the every-day needs 

 as the extremes, possibly even only the occasional extremes which the species 

 has to face in nature. 



An extensive bibliography is given. 



Studies on the progress of plasmolysis, K. Heciit (Bcitr. Biol. Pflanz., 

 11 (1912), No. 1, pp. 131-192, pis. 2, figs. 6).— The author reports that, in 

 studies made by him of plasmolyzed cells, he still observed, following the rup- 

 ture and separation of the cytoplasmic envelope from the cell wall, numerous 

 connecting threads of very different sizes, and also connecting with these a 

 protoplasmic network adhering closely to the cell wall. To both these struc- 

 tures, it is thought, both hyaloplasm and nucleoplasm contributed, microsomes 

 and chlorophyll grains being found together, particularly in the larger plasma 

 masses remaining near the cell wall. The presence of this lining, it is thought, 

 may be the result of some interaction of the plasmic components. 



The part played by living cells in sap ascent, A. Ursprung (Bot. Centhl., 

 BcUtefie, 28 (1912), 1. Aht., No. 2, pp. 311r322).—T\xe author discusses the work 

 of several other investigators as well as some of his own on this subject, con- 

 cluding with the assertion that the efforts of Dixon and Overton (E. S. R., 21, 

 p. 318; 25. p. 220) to refer the death of the leaves after partial death of the 

 stem to poisoning or to plasmolysis are not conclusive; also that the same may 

 be said in regard to Overton's defense of the view that sufficient water may be 

 carried past killed portions of the stem for the nourishment of the leaves. 



Studies on regenerative processes in plants, B. Kabus (Beitr. Biol. Pflanz., 

 11 (1912), No. 1, pp. 1-52, figs. 23). — Investigations were made on both the 

 underground and aerial parts of a considerable number and variety of plants 

 regarding their modes and rates of forming new tissue when wounded, as for 

 example in grafting, the conditions under which it occurs, and the factors favor- 

 ing or hindering its occurrence. 



It was found that cork formation in case of wounded potato tubers follows 

 access of air. Sugar formed at the cut surface in the presence of air was 

 partly withdrawn and partly utilized in the formation of wound periderm. The 

 cut cells turned brown on contact with air. The presence of eyes is not neces- 

 sary to the growing together at the cut surfaces by two tubers, but it does 

 hasten such union. Lower temperatures may prevent the union even of tubers 

 provided with eyes. The vascular bundles seemed to play an important part in 

 this process. 



In subterranean parts of Dahlia variabilis, Sauromatum guttatvm, and Bous- 

 singuultia baseUoides the presence of buds was not necessary to union, but it 



