66 SUMMARY OF CUKKENT RKSEARCHES KELATING TO 



effects of cross- and self-fertilization upon the formation of fruit and 

 seed. In eight species examined xenogamy produced the best results in 

 fruit formation ; in only one case — viz. in Tritonia aurea — was geitono- 

 garay more effective. The same results were obtained in con- 

 nexion with the size of the fruits and the number of seeds, except that 

 in three cases longer fruits were formed on geitonogamous or autogamous 

 plants. In most species the seeds were heaviest in xenogamitic fruits, 

 but in Primula sinensis geitonogamy produced the best seeds, and in one 

 variety of Brassica, in Toona, Hyacinthus, F7-eesiaLeicMlini, and Tritonia 

 aurea, the heaviest seeds were obtained from self-fertilized flowers. The 

 germination of seeds from xenogamous fruits was more certain in sverv 

 instance except iu T. aurea, where geitonogamous seeds were most pro- 

 ductive. The author therefore concludes that xenogamy is relatively of 

 greater importance than either geitonogamy or autogamy. 8. G. 



CRYPTOGAMS. 



Pteridophyta. 



Contributions towards a Knowledge of the Anatomy of the 

 Genus Selaginella.-- J C. Th. Uphoff (Annals of Botany, 1920, 34, 

 493-517, 13 figs.). An investigation of the anatomy of the root. 

 Summing up his work, the author says that SelayineUa is a remnant of 

 a group of primitive vascular plants, and therefore is of great interest 

 morphologically. Some living allies of SelagineUa have true roots, 

 though not very different anatomically from stems {Lycopodiuni) ; and 

 some have no true roots {Psilotum). Generally the root is simple in 

 construction and differs from the stem, the former lacking the lacuna.^ 

 and trabecule of the latter. There is no important anatomical differ- 

 ence between aerial and terrestrial roots. The difference of the outer 

 tissue is due to environmeutal circumstauces. Physiologically both 

 kinds of roots have the same characteristics in the same degree ; both 

 are negatively heliotropic. Eoots with root-cap always have root-hairs, 

 which are very rare in case of roots without a rootrcap. In all species 

 the root originates with regard to the stem exogenously ; the branching 

 is monopodial. Some species, when bruised, form small stems instead 

 of rhizophores ; these- suggested to many investigators that the latter 

 are leafless stems ; but the anatomy shows that these branches have the 

 same construction as a stem and are positively heliotropic, wdiereas 

 so-called rhizophores have the construction of a root and are negatively 

 heliotropic. The vascular system is monarch; the endodermis and 

 pericycle are always present. The phloem shows the same arrangements 

 as in the stem, although its elements are less abundant. The xylem is 

 composed of one group of protoxylem and usually a well-developed 

 metaxylem. The thick-walled tissue which follows the three layers of 

 thin-walled cells of the periphery of the terrestrial roots apparently 

 belongs to the hypodermis. A. Gepp. 



G-all-like rormation on Antrophyum semicostatum Bl. — 

 K. GiESENHAGEN (Ber. Deutsch. Bot. Ges., 1917, 34, 802-7; see 

 also Bot. CentralbL, 1918, 137, 168). On the margin of a frond of 



