270 JOURNAL OF THE EOYAL HORTICULTURAL SOCIETY. 



The hyaline tissue is regarded as a reserve tissue, in which also building 

 material is formed. — G. F. S.-E. 



Varying Sensitiveness of Boots. 



Roots, Rheotropism Of. By F. C. Newcombe (Bot. Gaz. xxxiii. 

 No. 3, p. 177 ; with 15 figs.). — After an historical review and the 

 methods adopted in the experiments, the author enumerates " plants 

 unsuited to experiment," in that when grown in moving water their roots 

 grow straight downwards (geotropically), unaffected by the pressure of 

 the current. Many roots also show contortion. Of thirty-two species 

 of nine families tested for rheotropism, fourteen were insensitive to the 

 water stream ; the rheotropic species were eighteen of six families. This 

 result proved that rheotropism is not a general phenomenon, especially 

 with normally aquatic plants. " It would seem to be of distinct dis- 

 advantage for such plants to be rheotropic in their roots ; for only by 

 insensitiveness to the flow of water can the roots the most quickly find 

 the solid substratum." 



Under rheotropism the roots turn up in opposition to the direction of 

 the current. Of plants insensitive the author mentions Allium Cepa, 

 Nasturtium officinale, Quercus alba, Cucurbita Pepo, Citrullus vulgaris, 

 Phaseolus sp. 



Then follow descriptions of plants having " a low degree of sensitive- 

 ness " and "plants with a high degree," of these a dwarf Maize, Wheat, 

 Rye, Barley and Oat, Pea and Buckwheat, Mustard, Cabbage, Brassica 

 campestris, and Radish. (The paper is to be continued.) — G. H. 



Evolution of Male and Female Organs. 



Sexual Organs, Homology of, in Development of Male and 

 Female. By K. Goebel (Flora, vol. xc. 1902, pp. 279-305).— The 

 author describes the cell divisions that form the nucule of Characcce, 

 compares them with the quadrant divisions of the antheridium, and points 

 out that the sterile " Wendungszellen " at the base of the oosphere are 

 clearly its coequivalents, like the "polar cells" of Metazoa and of some 

 Fucaccce, but aborted [a view put forward by the abstractor in " Some 

 Problems of Reproduction " in Quart. J. Micr. Sci. 1891, not quoted by 

 the author]. The function of these sterile potential cells is probably 

 nutritive. In Marchantiaccce the primordial cell of the antheridium 

 divides by vertical partitions into quadrants, each of which again divides 

 tangentially into an outer wall-cell and an inner spermatogenous cell. 

 In Jungermanniece the first division is followed by a symmetrical division 

 of either half into two : (1) a smaller cell which produces part of the wall ; 

 and (2) a larger cell which again divides to form a second wall-cell and a 

 spermatogenous cell. Goebel regards cell 1 as equivalent to a quadrant cell 

 of the Marchantiaccce, which is sterilised. This process goes further in the 

 archegonium of both groups, the first division separating a quarter wall- 

 cell from an unsterilised one which gives rise to the remaining wall- cells 

 and the axial row (oosphere and canal- and cap-cells). The first division 

 thus homologises with that of an antheridium one, (vertical) half of 

 which is sterilised from the outset, while the other half may be compared 



