HARDWICKE'S SCIENCE-GOSSIP. 



21 



in which the colour of the silk had been controlled 

 by the use of appropriate colours in the larval 

 environment at the time of spinning up. lie said 

 this colour-susceptibilty had been previously proved 

 by him in 18S6, in the case of Satitniia carpini, and 

 the experiments on the subject has been described in 

 the Proc. Royal Society, 18S7. It appeared from 

 these experiments that the cocoons were dark brown 

 when the larva; had been placed in a black bag ; 

 white when they had been freely exposed to light, 

 with white surfaces in the immediate neighbourhood. 

 Mr. Poulton stated that other species subjected to 

 experiments during the past season, afforded con- 

 firmatory results. Thus the larvre of Eriogaster 

 lacustris had been exposed to white surroundings by 

 the Rev. W. J. H. Newman, and cream-coloured 

 cocoons were produced in all cases, whilst two or 

 three hundred larvae from the same company shun 

 the ordinary dark brown cocoons among the leaves 

 of the food-plant. In the latter case, the green 

 surroundings appeared to act as a stimulus to the 

 production of a colour which corresponded with that 

 which the leaves would subsequently assume. Mr. 

 Stainton suggested that larvae should be placed in 

 green boxes, with the view of ascertaining whether 

 the cocoons would be green. It had been suggested 

 that the cocoons formed amongst leaves became 

 brown because the larvae knew what colour the leaves 

 would ultimately become. 



BOTANY. 



Tree-growing after Girdling. —In May, 1879, 

 I attempted to kill by girdling a tremulous poplar- 

 tree, which, by its position and the numerous suckers 

 it threw up from its wide-extending roots, interfered 

 with my orchard. I cut off a strip of bark twelve 

 inches wide entirely around the tree, at a spot about 

 a foot from the surface of the earth. The part left 

 bare seasoned over that year, but the tree did not 

 die ; however, it shed its leaves earlier than others of 

 the same species. It grew on the next year, as if 

 nothing were the matter till the autumn, when the 

 foliage assumed unusually brilliant colours of red 

 and yellow a full month before there was any change 

 on the other trees. It continued growing during 

 the third year subsequent to the girdling, but with 

 diminished energy, and the leaves changed their hue 

 at the close of summer, and fell very early in autumn ; 

 and next spring, 1881, the tree was quite dead. I 

 should mention that it did not put out its leaves just 

 so early in the spring after being girdled, as it would 

 otherwise have done. I have read in the " Scientific 

 American " of a somewhat similar experiment, with 

 the difference, however, that the Vermont tree kept 

 growing on above the ring, and increased in three 

 years five inches in circumference above, while it 



remained of the same girth below. There was no 

 such exceptional phenomenon in the tree with which 

 I dealt in co. Armagh.—//. W. Lett, M.A. 

 Flowers and Fruits.— At pp. 11 and 12 of Dr. 

 . Taylor's most interesting and suggestive " Sagacity 

 and Morality of Hants," I find, " A leaf is a much 

 more highly-organised vegetable production than a 

 petal. . . . Flowers are frequently terminal . . . 

 borne . . . where the uprising sap . . . must be 

 poorest and thinnest." This, of course, I quite 

 understand. On pp. 14 and 15 there are descriptions 

 of flowers of the gentians, etc., being produced "at 

 great physiological expense " to the plant ; added to 

 this, of course, it is well known that plants expend a 

 great deal of energy on the all-important process of 

 ripening their seeds." I should be glad if any one will 

 explain how fruits obtain the amount of nourishment 

 they require for this purpose, placed as they are in 

 the same position on the plant as the flowers, which 

 are, to a great extent, because of their position 

 "aborted and degraded" and starved leaves. — A. G. 

 Tansley. 



Yew-Trees, their Size and" Age. — I have been, 

 with my friends, measuring several big yew-trees in 

 the south-east corner of Hampshire. Will you allow 

 me to state the result in Science-Gossip, with a- 

 view to learning about other big yews, and with a 

 view to description as to their age ? I give the cir- 

 cumference — the smallest circumference of each of 

 four trees in three neighbouring churchyards. 



ft. in. 



1. In Warblington Churchyard . 18 4 



2. ,, Redhampton ,, . 20 o 



3. „ do. ,, . 20 5 



4. ,, S. Hayling „ . 33 o 



Reckoning a year for every line of diameter, or 

 twelve years for every inch, this would give to the 

 Hayling tree, with a diameter, say, of 11 feet, or 132 

 inches, an age of 1584 years. Will any of your 

 readers contribute any information as to big yews ; 

 their size, and the mode of ascertaining the age ? — 

 P. J., Emsivorth. 



Campanula glomerata. — I was very much sur- 

 prised to find a number of plants of this species in 

 full flower in the first week of the present month of 

 November. They were on the Downs, near Beachy 

 Head. I suppose this unseasonable blossoming is to 

 be attributed to the plants having been kept back by 

 the extraordinary drought of the past summer. I 

 found, too, on the loth of November, plants of 

 Gentiana campestris in flower ; these, too, I suppose,, 

 had been delayed by the drought. Those botanists 

 who have only seen C. glomerata in localities where 

 it attains its normal development, would scarcely 

 recognise it as it is found here, where it does not 

 exceed an inch or an inch and a half in height, and 

 where it usually has only one flower, which looks 

 like a little blue star, as it peeps out of the short 

 grass. — R. B. P., Eastbourne. 



