NOTES ON RECENT RESEARCH. 



891 



Anatomy of Grasses. 



Grass Anatomy {Beih. Bot. Cent. bd. xi. ht. 2 ; pp. 101-134; two 

 figures). — Dr. Holm (Brookland) has examined the leaf -structure of many 

 species of Aristida, StijM, Oryzopsis, Eriocoma, Nassella, Piptochcetiuvi, 

 Mulilenhergia, Ly citrus, Sporobolus, &c. He has found that in most 

 species of Aristida (and only in this genus) the leaf vascular-bundles are 

 siirrounded by a double parenchyma-sheath which contains chlorophyll. 

 Those species which have this structure have no mestome and very little 

 thick-walled mestome parenchyma. — G. F. S.-E. 



Heterogenesis and Evolution. 

 Heterogenesis and Evolution. By S. Korschinsky (deceased). 



Director of the Botanic Gardens of St. Petersburg {Flora, \ol. Ixxxix. 1901, 

 pp. 240-363). — This posthumous paper treats of the phenomenon dealt 

 with mainly in animals by Bateson (who is not cited in the bibliography), 

 under the name of "Discontinuous Generation," and comprises a wide 

 survey of its occurrence in flowering plants. The recorded occurrences of 

 the phenomenon are described in order : — (1) Variations in growth : (a) 

 gigantism and nanism, {b) in stem and its armament, (c) in the habit 

 of the leafy crown of trees ; (2) leaf-form ; (3) leaf-colour ; (4) flower- 

 colour ; (5) flower-structure ; (6) mode and Lime of flowering ; (7) fruit. 



From a study of the records it is probable that any given hetero- 

 genetic variation makes its appearance in a single individual only ; 

 apparent exceptions are probably due to the variation having occurred 

 unnoted a generation earlier or to hybridism. As a cause of hetero- 

 genesis it seems probable that too much weight has been laid by breeders 

 on high cultivation, which may however be efficacious to some extent, 

 for the fact of high cultivation is associated with careful and unwearied 

 search and selection. Variations may be classified as regressive 

 (atavistic), progressive, and indiff^erent. Heterogenesis is often accom- 

 panied by altered physiological qualities, such as diminished reproductive 

 (sexual) powers, weakness of growth, susceptibility to frost. They vary 

 in the constancy of transmission by seed, not only in the original, but 

 also in subsequent selected generations. The immediate cause of hetero- 

 genesis probably lies in some alteration of the seed- origin (Anlage during 

 or after fertilisation). — 31. H. 



Leaf Anatomy. 



Leaf-anatomy of Australian Podalyrieae (Beih. Bot. Cent. hd. xi. 

 ht. 3, pp. 143-217, plate). — Herr Paul Hiihner describes the anatomical 

 characters of Gastrolobium (14 species), Pultencea (46 sp.), Latrobea 

 (4 sp.), Eutaxia (5 sp.), and Dillwynia (14 sp.). They appear to show 

 very distinct xerophytic characters. The leaf is generally centric ; the 

 nerves are imbedded in sclerenchyma ; stomata occur generally on the 

 lower surface ; the inner cell-w^all membrane of the epidermis cells is often 

 gelatinous. Crystals, sphsero-crystals, and idioblasts are common. The 

 paper is almost an impossible one to abstract, as each leaf in the 88- 

 species investigated has its own individual differences, which are given in 

 detail.— (r. F. S.-E. 



