238 BOTANICAL GAZETTE [September 



layer that gives rise to lateral roots, and hence are morphologically lateral 

 roots ; that tubercles are largest and most numerous near the surface of the 

 soil ; that the presence of bacteria prevents the infected cells from forming 

 starch grains; that the bacteria cause the degeneration and almost complete 

 destruction of the nuclei ; that infected cells soon lose the power of division, 

 though not of growth ; that the relation of the bacteria to their host-cells is 

 parasitism ; that it is difficult to understand how the plant as a whole can 

 profit by an association which injures and finally destroys the cells. — J. M. C. 



LuiGi BUSCALIOXI," in an extensive preliminary notice, describes his 

 studies on the development of the root in the monocotyledons. His restilts 

 are new and interesting in many respects; and their early publication in extenso 

 is to be desired. The author calls attention to the fact that in the root of 

 the same species the periblem and plerome may originate from a common 

 meristem, or have distinct and separate initials according as the root is of 

 larger or smaller size. The medulla in the case of large roots often shows its 

 community of origin with the cortex by the presence of raphide cells such as 

 are characteristic only of the extrastelar fundamental tissues. The apparent 

 medulla, which is often present in smaller roots, the author does not consider 

 to be a true medulla, and designates it medullifonn tissue. These results are 

 of great interest from the standpoint of existing stelar hypotheses. The root 

 would seem to be a specially favorable organ for the investigation of these 

 problems, both on account of its primitive structure and the clear limitation 

 of the primary meristems. Another novelty is the announcement that the 

 origin of the tracheary elements of the root is centrifugal, in spite of the fact 

 that the order of their lignification is centripetal. In the Dioscoreaceae and 

 Asparagaceae, the mother cells of the tracheary elements are multinucleate. 



— E. C. Jeffrey. 



L. GuiGNARD^^ has added certain Solanaceae to the list of plants in 

 which "double fertilization" has been observed. His work was chiefly with 



^ 1 was seen of N, riistica, 

 D. stramonium, ;xi\i. Z>. Tatula to indicate that they exhibit the same phenome- 

 non. In Nicotiana the generative cell divides in the pollen grain, while in 

 Datura it divides after entering the pollen tube, and in both cases the male 

 cells are small and ovoid, or very slightly elongated. In Datura a remark- 

 able change in the form of the tube nucleus was observed to occur in the 

 tube, a very much elongated and irregular filamentous form being assumed. 

 In both genera the tube enters a synergid and discharges, the two male cells 

 rapidly approaching the egg nucleus and the polar nuclei. In Nicotiana the 



»' Suir anatomic de cilindo centrale nelle radice delle Monocotiledoni. Malpighia 

 15 ■ 276-296. 1902. 



"La doable fecoiidatioa chez les Salan^es. Jour. Botanique 16 : i45-i67- fi^^' 

 45' 1902, 



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