116 



HARDWICKE'S SCIENCE-GOSSIP. 



the same efifect. Certain plants are known to 

 have a peculiar power of absorption and evapora- 

 tion : florists find such to be the case, for instance, 

 in the Spircea Japotiica, which on that account re- 

 quires watering several times a day, or to be kept 

 standing in water. Whatever may ^e the cause of 

 its sanitary effects, the subject is interesting, and 

 calls for further elucidation as to the characteristics 

 of the tree and its medicinal properties. — T. B. W. 



Flower-buds on Roots.— W. G. Piper asks if 

 flowers are found on the root in other plants, as in 

 the Theohrcma cacao? The Catananche Intea, in 

 all the numerous specimens I have met with 

 in Algeria, has several flowers on the crown of the 

 root, the others being at a distance at the top of 

 the stem. The Ficia ampkicarpa has the upper 

 flowers and legumes above ground, the lower sub- 

 terranean. I met with it at Montpellier, but do 

 not remember whether the subterranean flowers 

 had underground stems or grew direct from the 

 root.— r. B. W. 



Genista pilosa (Hairy Greenweed) as a Sea- 

 side Shrub. — The latter end of February I saw a 

 branch of this small shrub, which was sent from 

 Poole, in Dorsetshire, where it grows spontaneously 

 in great abundance close to the harbour: it was 

 then commencing flowering, the flowers bright 

 yellow and very abundant : it is a rare British 

 evergreen, much branched and prostrate, and 

 flowers from very early spring till the autumn. Sir 

 William Hooker, in his " British Flora," gives only 

 four localities, one of them being "near the Lizard 

 and St. Agnes Head, Cornwall," where, as well as 

 at Poole, it thrives close to the sea. Mr. Balchin, 

 of the Cliftonville Nursery, is about to introduce 

 it in Brighton, with any other seaside shrubs which 

 the readers of Science-Gossip may bring to his 

 notice. The Genista pilosa cannot fail to be at- 

 tractive as a pretty evergreen border shrub, suited 

 to the climate of Brighton, as well as for inland 

 cultivation. — T. B. W., Brighton. 



Bulbiferous Stem of Saxifraga granulata. 

 — In reply to Mr. Piper's query in last month's 

 Gossip, 1 beg to say that the bulbs occurring in the 

 stem of the Saxifraga granulata are not of the 

 nature of the bulbs mentioned by Bentley in his 

 " Manual of Botany," as exclusively, belonging to 

 the class Endogence ; those being bulbs proper, 

 without reference to any other than such to which 

 the following description will apply. "A thickened 

 underground stem, covered with scales, emitting 

 roots from its under surface, and producing a stem 

 from its centre." Such, then, and only such as 

 bear this definition, are true bulbs, of which the 

 Onion and Squill are familiar examples. Every true 

 bulb is, therefore, necessarily formed of imbricated 

 scales, and a solid bulb has no existence. For 



instance, the bulbi solidi, as they have been called, 

 though erroneously, of the Crocus and Colchicum, 

 are a kind of subterranean stem, and which, though 

 perhaps the nearest approach we have to the bulb, 

 still are considered to be sufiiciently distinct and 

 marked from it, in consisting not of imbricated 

 scales, but '■ of a solid fleshy mass. . Therefore I 

 should say of the descriptions applied by Hooker 

 and Bentham to the characteristic stemi of the 

 Saxifraga granulata, and which I find myself alike 

 applied by other writers on botany to stems simi- 

 larly characterized, that they are not intended by 

 them to be applied in the above strictly botanical 

 sense, but only in suchwise where the descriptions 

 are based — and this is exactly how I take them to 

 be— upon an external resemblance to, rather than 

 to a partaking of the nature of, the true bulb ; or, 

 in other words, I regard them, in all such cases, as 

 being adopted more upon the principle of sug- 

 gestiveness than of strict botanical applicability. 

 Again, and lastly, were they true bulbs, then there 

 must, in such a case, be as many stems as bulbs, 

 since, as[we have seen, each is possessed of a stem- 

 producing centre, which, in the so-called bulbi- 

 ferous stem of the Saxifraga granulata, we know 

 is not the case. — John Harrison, 41, Wicker, Shef- 

 field. 



GEOLOGY. 



The Physical History of thr Bhine 

 Valley. — At a meeting of the Geological Society 

 of London, Professor Ramsay stated that his opinion 

 was that during portions of the Miocene epoch the 

 drainage through the great valley between the 

 Schwarzwald and the Vosges ran from the Devo- 

 nian hills north of Mainz into the area now occupied 

 by the Miocene rocks of Switzerland. Then, after 

 the physical disturbances which closed the Miocene 

 epoch in these regions, the direction of the drainage 

 was reversed, so that, after passing through the hiU 

 country between the Lake of Constance and Basle, 

 the river flowed along an elevated plain formed of 

 Miocene deposits, the remains of which still exist at 

 the sides of the valley between Basle and Mainz. 

 At the same time the Rhine flowed in a minor 

 valley through the upland country formed of 

 Devonian rocks, which now constitute the Taunus, 

 the Hundsruck, and the highland lying towards 

 Bonn, and by the ordinary erosive action of the 

 great river the gorge was gradually formed and 

 deepened to its present level. In proportion as 

 the gorge deepened, the marly flat Miocene strata 

 of the area between Mainz aud Basle were also in 

 great part worn away, leaving the existing plain, 

 which presents a deceptive appearance of having 

 once been occupied by a great lake. 



