582 SUMMARY OF OUllRENT KESEARCHES RELATING TO 



B. suhglohosum and to B. pallescens, speaks of the hesitation which has 

 prevented him for some years from adding to the already perplexingly 

 nnmerous species in that genus, and of the long study which he has 

 bestowed upon such variable species as B, pendulum, B. arcticum, B. 

 incUnatum, and B. ^xdlescens. A certain number of European Bnja have 

 never been found but once. It is absurd to suppose that they were old 

 species now extinct, or new species in process of formation. They must 

 have been accidental forms which have failed to establish themselves. 

 If they had survived, their characters might have become fixed. "What 

 we want in a genus so prolific in varieties and forms is to test the 

 coefficient of constancy of the characters of these forms, in order to 

 determine how far this constancy avails as a basis for the creation of 

 new species. 



Rearrangement of Drepanocladus and its Allies.* — L. Loeske, in 

 showing that Drepanocladus is a biological conglomerate of genera, takes 

 the view that, though in the mosses as a whole there is no substitute for 

 the sporogonium as a basis upon which to found a classificatory system, 

 the variation of form manifested by the acrocarpous sporogonium 

 being of great importance, yet in the Hypneee at least a limit must 

 be set to the value attached to the sporogonium as a generic character. 

 Loeske holds that the ancestors of the Hypneae had already developed 

 their sporogonium almost to its fullest capacity at a time when the 

 vegetative part of the plant was first entering upon the period of its 

 most active development ; hence the descendants, though they have 

 developed great morphological differences in their vegetative organs, 

 retain practically the same sporogonium. He maintains that plants 

 which have a similar sporogonium do not therefore necessarily belong 

 to one and the same genus. Having devoted months of study to every 

 available species and form, he has at last come to definite conclusions — 

 inter alia, that Drepanocladus is a biological mixture of genera. He 

 discusses such characters as the single or double nerve, the serrated 

 margin, the uncinate leaves, etc. He recognises three well-marked new 

 genera : Sanmiia, Limprichtia, Warnstorjia, which take equal rank with 

 Drepanocladus (reformed), PseudocalUergon (new genus) and Scorpidium. 

 1, Sanionia (named after Sanio) includes Hypnwn fertile, H. uncinatum 

 with all its forms. 2. Limprichtia includes H. vernicosum, H. inter- 

 medium (with H. Cossoni), and H. revolvens. 3. Warnstorjia includes 

 Hypnum exatmulatus, H. fluitans, H. purpurascens, H. tundrce, etc, 

 4. Drepanocladus ret'dinB the Kneiffii and Sendtneri gvou])8. 5. Fseudo- 

 calliergon includes the orthophyllous species H. turgescens, H. trifarium, 

 and iff. longicuspis. 6. Scorpidium contains H. scorpioides. The first 

 three of these genera he places in the new group Dr€2)anopsis allied to 

 the Stereodontea3 ; and genera (4) to (6) he puts into group Drepano- 

 cladus allied to Amhlystegium. Leaving this subject, the author gives a 

 series of notes on various subjects ; for instance, since pubHshing a 

 recent paper on the relationships of the European Brachytheciese, he has 

 discovered a connecting hnk for Camptothecium with Brachythecium 

 through the B, salehrosum group. Again, he holds that Thuidium, 

 Gratoneuron and Amhlystegium are very closely allied ; and that 

 Cratoneuron and HygroamUystegium have probably arisen from a- 



• Hedwigia, xlvi. (1907) pp. 300-21. 



