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Show 292 MODIFIED CIRCUMNUTA'l'ION. C II AP, VI. .Melilotus macror-r·hizct.-The plants were exposed in tho snmo manner as in the last case. Six leaves bad boon pinned out horizontally, and five of them were killed, that is, 83 per cent. We estimated that there were 200 free leaves on tho plants, and of those about 50 were killed and 20 badly injured, so that about :-15 per cent. of the frco loaves were killed or injured. Lotus aristata.-Six plants wore exposed for nearly 5 h. to a clear sky; temperature on surrounding O'rass - 1·5° C. Four leaves had been piuned out horizontally, and 2 of those suffered more than those above or below on the same branches, which had Leen allowed to go to sleep. It is rather a remarkable fact that some plants of Lotus Jacobce1ts, an inhabitant of so hot a country as the Cape Verde Islands, were exposed one night ton clear sky, with the temperature of the surrounding grass- 2° C., n,ncl on a second night for 30 m. with the temperature of the grass between - 3° ttnd - 4° C., all(l not a single leaf, either the pinned-out or free ones, was in tho least injmed. Marr·silea qttad?'lfoliata.-A la.rge plant of this species-the only Crypto<Yamic plant known to Rlcep-·wit.h some lca\CS pinned open, was exposed for 1 h. 35m. to a clear sky, tho temperature on tho surrounding ground being - 2° C., aud not a siuglc leaf was iujured. After an interval of some cln.ys tho plant was again exposed for 1 h. to a clear sky, with tho temperature on the Rurronncling ground lower, viz., - 4° C. ix ]eaves ltnd been pinned out horizontally, and all of th m were utterly killed. The plant had emitted long trailinp- sten1S, and tltesc had Leon wrapped round with a blanket, f;O as to protect them from tho frozen ground and from radiation; lint a very large number of leaves were left freely exposed, which had gone to sleep, and of these only 12 wore killed. After another interval, the plant, with 9 leaves pinned out, was again exposed. for lh., tho temperature on tho ground being again - 4° C. Six of the leaves were killed, and one which did not at first appear injured after· wards became streaked with brown. 'rho trailing braneheR, which rested on the frozen ground, had one-half or three-quarters of their leaves killed, but of tile many other leaves on tho plant, which alone could be fairly compared with tho pinuecl-out ones, nono appeared at first sight to have been killed, but on careful search 12 were found in this state. After another interval, the plant with 9 leaves pinned out, was exposed for 35-40 m. to a clear sky and to nearly the same, or perhaps a rather lower, tempera· ture (for the thermometer by an accident had been left on a CnAr. VI. U E OF SLlDEP MOVEMENTS. 20:3 sun-dial gJose by), and s. ~f these leaves were killed. Of tho free leaves (those on the tn11lmg branches not boing cons'd . d) d k . 11 1 1 ere , u, go~ . many wore 1 ec., but their number, compared with the unmJurcd ones, was small. Finally, taking the three trials tog~ther, 24 leaves, extended hori>wntally, were exposed to the kz'eJJm dth adn d t· o · unobstruc. ted radiation ll''ld of tl 20 < ' ~ 1ese were fI tch a1n 1 InJur·e d; whilst a relatively very small propor tw' n o e cav~s, whrch had been allowed to go to sleep with their leaflets vertrcally dependent, wor·o killed or injured. The cotyledons of several plants were prepared for trial b t ~hehwe~ther was .mild and we succeeded only in a single instan~o m avmg seedlmgs of the proper ago on nights which were ~ear and cold. The cotyledons of 6 seedlings of Mimosa purl icn t ere fastened open on cork, and were thns exposed for 1 h 45 m a~ a2~~e; ~k~, with tho tomper:ature on the surrounding ~round th . t. 'l ~ these, 3 wore killed. Two other seedlings after eir coY c ons had rism1 up and had closed together' wore ~ent over and fastened so that they stood horizontally with tho bo7~r surfac~ of one cotyledon fully exposed to the zdnith and m~re ~~:: ~rlled. 'l'hCI:efore of the 8 seedling thus tried '5, or cotyledons in a!i' ~er·e ~nlled. oven other seedlings, with their closed we lOir :01mal nocturnal position, viz., vertical and killed',.. ~e exp~se at tho same time, and of those only 2 wei·e that th ~t~ce rt a~p.ears, as far as the o few trials tell anything, pudica e r:~:c~cal positiOn at nig_ht of tho cotyledons of Jlfimosn radiat' p d s them to a certam degree from the evil effects of wn an cold. at GN:o~chluding_ Remarks on the Radiation from Leaves su ~g t.- We expose-d on t wo occasw· ns durino· tho of mTm iefri z·t o a clea r. s k y sovera1 pl. uned -open leoa flets and rf~ Oo ~uln: pratense, which naturally rise at nio·ht o xa~spur'P l' h b ' (the lant . _urea, w uc naturally sink at night p s growmg out of doors.), and looked at • We were · young seed!' surpnsod that plant as M' Ings of 130 tropi<'al a to resi~t a:mosll pudica wore able poaure f~r 1 he as they did, oxskv the t r. 45 m. to a clear roii~din emperaturc on the sur-g ground being 29o li'. It mn.y be added that seedlings of tho Iudin.n Cw;sia pubescens were exposed for 1 h. 30 m. to a clear sky, '~ ith the temp. on the surroundmg gro~nd at- 2° C., and they were not m the least injured. ...' I , ,, ,I,•,' II |