SCIENCE- GOSSIP. 



227 



and Polytrichia)! K/x/i/if/ularfl. In the remaining 

 orders of this group, Buxbaumiaceae and Tetra- 

 |ihi(laceae, I could find no decided twisting in my 

 examples of any of 1 he Bril ish species. 

 In the Aplolepideae the seta is frequently 



flexunse, and sennet hues strongly twisted. The 

 peristome teeth and even the capsule itself are 

 also occasionally contorted. In Dicranwm the seta 

 is Hexed, hardly twisted, to the right in most cases, 

 but in B. longifolium occasionally to the left. In 

 Ditricltii hi pallidum and B. liomomalltim it gyrates 

 to the right, but in some specimens of I), tcnui- 

 folium to the right below and left above. In 

 Swa/rtzia Montana there is a rather strong twist to 

 the right, whereas in the closely allied S. inclinata 

 the spiral turns more feebly to the left. I was 

 unable to satisfy myself of any tendency to twist 

 in Blindia ; but in some examples of Seligeria 

 re&u/rvata and 8. paucijiora the seta gyrated to the 

 right ; in other species, >S. pusilla and S. calca/rea, 

 the reverse was the case, and in S. doniana it twisted 

 to the right at the base and to the left at the 

 summit. This curious twisting in two directions 

 is very noticeable in the seta of Brachyodiis 

 trieliodes. A decided twist is noticeable in some of 

 the Dicranellae, to the right in Bicranella varia 

 and D. sehreberi, to the left in D. rufescens, and 

 occasionally left below and right above in D. 

 sqiinrrosa, B. lief ero mall a. B. ccrviculata, and 

 B. subulata. In Bicranoiveisia and some species 

 of Campylopus there is sometimes a feeble twist- 

 ing to the left, also in ffliabdoweisia denticulata 

 and B.fugax, in the latter species sometimes very 

 strongly marked. The seta of Leuodbrywm glaucvm 

 is often strongly twisted to the right. 



The setae of the Fissidentaceae display evidence 

 of only very weak twisting. I found right spirals 

 in some examples of Fissidens viridulus, F. taxi- 

 folius, F. bryoides, and F. decipiens, and left ones in 

 F. rivularis, F. exilis, and F. osmiindoides. In 

 many of these twisted setae are so rare that they 

 might be considered accidental. 



In Gximmiaceae, amongst a large number of 

 species of Gfrimmia examined, I did not find any 

 with the seta twisted to the right, though those 

 exhibiting left spirals were not infrequent. On 

 the contrary Wiaeomitrium, which is so closely 

 allied as to be considered congeneric with Grwimia 

 by some distinguished authorities, exhibits a 

 majority of Left twisting species, e.g. Rliacomitrium 

 protensiun, R. aoiculare, R. heterostickim, and 

 /.'. microcarpon, only R. can exec ns of those I 

 examined being contorted in t he opposite direction. 

 In Ptychomitrinm polypliyllum also the direction 

 is usually to the left. 



Tortulaceae. -In the genera PotHa and Tortilla 

 there is a move or less well developed twist to the 

 left, except in a few instances, e.g. PotHa cri/nita 

 and Tortula angustata, in which the spiral turns to 

 the right below, but higher up conforms with the 

 direction taken in the other species. In Barbula, 



on t he contrary, the direction appears to be to the 

 right where any twisting at all La displayed, the 



same being the case with I'rirJiiistoniiim tortlC08Wttl. 

 The peristome of ! the Tortulaceae appears to twist 

 to the left much more constantly than does the 

 seta, and the two therefore occasionally form 

 spirals having opposite direel ion-. 



In Encalyptaceae, Encnly/iln riih/arix, I'., apophy- 

 sata, A', brevioolla, I', rhabdoearpa, A. streptocarpa, 

 and E. alpina have the seta twisted to the right 

 witli varying degrees of intensity, ami only in 

 A', rilinta have I seen any tendency of the revolu- 

 tions to take the other direction. 



The Diplolepideae come next, of which I only 

 propose to touch on the acrocarpus section. In 

 the Orthotrichaceae, Schistostegaceae, and Brya- 

 ceae, strongly twisted setae are rare. An occa- 

 sional tendency to twist to the right may be seen 

 in Zygodon viridissimus, Anoeetangium compactwm, 

 Bryum capillare, B.warueum, and Weber a albicans. 

 In the foreign Bryum salinum the rotation is often 

 more strongly evident. It may also be traced in 

 Mnium cuspidatum, M. insignc\Si\v\ M. svbglobomm. 

 Of those twisting to the left with varying intensity, 

 but mostly rather feebly, may be enumerated 

 Bryinn pattens, B. ralop/iyttinii, B. pendulum, 

 B. alpinuiit, Webera cruda, Oreas niartiann. Mnium 

 undulatwm, and 31. medium. I have seen very 

 strongly twisted setae sometimes in Brijum tur- 

 binatuni. Mnium spinulosum has the seta twisted 

 to the right below and to the left above, and the 

 same condition is sometimes more feebly exhibited 

 by M. hormim, Webera glarialis, W. elongata, and 

 ( 'iitrlidiinu stygium. 



Of the Splachnaceae there is sometimes a twist 

 to the left, in iSplachnum sjiJu/rririiiu. and more 

 strongly and frequently in Oedipodium griffitli ia/num . 

 Of the Funariaceae, Fitnaria attenvata and F. erice- 

 toruin twist to the left, and Physcomitrivvi 

 sphaerioum to the right. Fuuuriu hygrometrira 

 sometimes twists to the left below, and to the right 

 above. Meesia uligiosa, Amblyodon dealbatus, and 

 7'imiuia bavariea twist to the left, as do Conostomum 

 boreale, Catoscopium nigritttm, Avlaeomniiim hetero- 

 stiehum, and ,1. androgynum. 



All these observations were made from dried 

 specimens, the setae rarely showing any marked 

 tendency to twist in the moist condition. In some 

 of the species quoted the phenomenon is so rare 

 that a large number of specimens were examined 

 before an example could be found, and in such 

 cases the twisting is probably accidental. In 

 other instances, every tuft contains numerous 

 examples, and the twisting appears to be a normal 

 condition of the species, although even in these the 

 degree of twisting varies considerably, being 

 affecte I by the age of the plants, and perhaps by 

 other circumstances. The spiral may consist of 

 only one or two feeble turns extending the length 

 of the seta, or the torsion may be so strong that 

 the coils resemble the twisted strands of a 



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