200 SUMMARY OF CURRENT RESEARCHES RELATING TO 



pyriforme, and P. splicer icam, and gives a detailed account of his results. 

 He states that just as Funaria hybrida, Ditrichum Breidleri, D. 

 astomoides are hybrid mosses of known parentage, so also is Physcomi- 

 trella Hampei, the mother of which is always P. patens, but the father 

 may be either PJvyscomitrium sphcp/ricum or P. pyriforme or P. eurysto- 

 mum. The author very carefully describes the structure of the respective 

 parents and of the resulting hybrids. He finds that the hybrids in their 

 vegetative parts (oophyte) correspond with the mother species, P. patens ; 

 but in the asexual generation (sporophyte) they inherit the characters of 

 the father species. 



Parallel Forms and Variability of Cell-length in Mosses.* — 

 L. Loeske has been studying the parallelism of forms in various species 

 under the influence of similar external conditions. In this sort of 

 work the study of herbarium specimens is of very little help ; the plants 

 must be observed in their natural habitats. He discovered a new variety, 

 Hygrohypnum subsplmricarpum var. cataractarmn, in a cascade in Algau, 

 a form remarkable for the long and even excurrent costa in its leaves 

 (the costa of the type being but three-quarters of the length of the leaf). 

 He thereupon turned his attention to Amblystegium fallax and its var. 

 spinifolium, which Roth and others claim to be a distinct species ; and 

 he has come to the conclusion that A. fallax is a flowing- water form of 

 A. filicinum, that A. fallax var. spinifolium is a parallel form of 

 A. irriguum, and A. noterophiloides a parallel form of A. fluviatile. 

 Warnstorf indeed combined the two latter into one species. Gratoneuron 

 irrigatum is, Loeske thinks, a mixture of parallel forms of G. commuta- 

 tum and G.falcatum growing in mountain streams. The rest of Loeske's 

 paper treats of the increase in length of the prosenchymatous cells of 

 the leaf in species of Gratoneuron and Hygroamblystegwm, this lengthening- 

 being proportional to the increased length of the leaf under the influence 

 of running water ; this is associated with a strengthening of the midrib. 

 Loeske recounts some observations made by him of change of form in 

 mosses under change of environment. 



Ramification in Muscineae.t — M. Servit has been incited by the 

 researches of Yelenovskv to examine the mode of branching in Muscineae. 

 On the whole he confirms the results of that author, but he also publishes 

 fresh observations and adds to those already made. In liverworts two 

 modes of ramification are recognised : (1) the terminal branching in 

 which the branches arise exogenously ; (2) the intercalary endogenous 

 formation of shoots. Leitgeb distinguishes two modifications of the 

 former method. This division is based on the behaviour of the shoot 

 in an early stage, but the present author shows that the fully developed 

 plant does not always correspond with the young stages. Velenovsky 

 describes certain so-called angular leaves (angular blatter) for the vas- 

 cular cryptogams only, but Servit here describes and figures similar 

 growths for liverworts, notably Mastigobryum trilobatum, where this 

 axillary bract is inserted on two branches. He discusses monopodial 

 and dichotomous branching as it occurs in the hepatics, in which group 

 the former mode of branching characterises the erect growing species, 



* Allgem. Bot. Zeitschr., xiii. (1907) pp. 119-22. 



t Beih. Bot. Centralbl., xxii., Abt. 1 (1907) pp. 287-93 (figs.). 



