October 1, 1894.] 



KNOWLEDGE 



237 



fuuctiou. The coloration of galls is perhaps also pro- 

 tective in some cases. Protection is needed especially 

 against birds, some of which break open galls to get at the 

 grubs they contain. 



Besides the bedeguar a red globular gall, that of 

 U. tyhinh'i-ia, is common on the leaves of the dog-rose, 

 and all our native roses are galled by Cynipids. In these 

 rose-galls species of Periclistus take up their quarters as 

 inquilines ; ichneumons may also be present as parasites. 



The galls of Andrinis mliens are known in California 

 as " flea seeds," from their jumping about on the ground ; 

 this results from the spasmodic movements of the larva 

 inside the thin-walled cavity of the gall. Another 

 Californian gall has been described as covered with mobile 

 hairs, which are sensitive to touch like the leaves of the 

 mimosa. Very remarkable, too, is the relationship sub- 

 sisting between the Cynipid* and figs. Certain species of 

 saw-fly deposit their eggs in the seed-vessels of the florets 

 in the interior of the wild fig. When fully developed the 

 saw-flies emerge, covered with pollen obtained from the 

 male flowers near the opening of the fig. Following an 

 ancient custom, the Greeks and Italians bang up bunches 

 of the wild fruits on their cultivated fig trees, and the 

 poUen-covered tiies which escape from them enter the 

 cultivated figs and fertilize the female florets in their 

 interiors. This operation is known as caprification. The 

 figs of the wild variety might almost be described as galls, 

 since they serve as hatcheries lor the saw-flies. Each 

 species of fig would further appear to have its own special 

 saw-fly. The Dead Sea fruit, or apples of Sodom, '• which 

 tempt the eye but turn to ashes on the lip," are probably 

 galls on a species of oak produced by Cynips i)is(jna, 

 though some suppose that the reference is to the fruit of a 

 species of Asclepias. 



We come now to the galls of the Cecidomyidae. In this 

 country one has not far to seek for them ; just at present 

 the galls of Cecidomi/ia urtictT are very abundant on the 

 common nettle. They grow on difl'erent parts of the plant 

 as irregular swellings, sometimes on the basal lobes of the 

 leaf, often as irregular masses on the inflorescence. 

 When opened, each cavity is seen to contain a single white 

 larva. 



On the umbels of the wild carrot, which is just now 

 coming into fruit, here and there one may find a fruit 

 enlarged to twice the ordinary size. Each loculus of the 

 two-celled ovary is occupied by a single orange-coloured 

 grub of Cecidomyia. Older galled fruits which have 

 been vacated are also to be seen, with two little round 

 holes at their base, through which the larva? have made 

 their exit. This species completes its metamorphosis 

 outside the gall, but numbers of the gall-midges spin their 

 cocoons within it, and only leave the gall as winged insects. 

 Swollen stems and leaves are very common on the lady's 

 bedstraw and other species of Galium. These yellowish- 

 green galls are produced by the gall-midge C. (jalli. 

 ('. campti/iula, as its name indicates, gives rise to globu- 

 lar and ovate galls on the harebell [Cnmjiunulu wtundi- 

 fiiliii). Other midges gall ihe flower-buds of the whin and 

 broom, the ovary of the violet, the catkins of the birch, 

 the leaves of the ash and willow, the leaf-stalks of the 

 poplar, and the fronds of the bracken. It would occupy 

 too much space to enumerate all our native plants on 

 which these dipterous galls occur. Such a list will 

 be found in Prof. Trail's papers in the Srotlish 

 yatiiralist. Suflice it to say that one has only to look 

 for them to find them, since they are borne by a large 

 proportion of our native wild flowers. The species of 

 Cecidomyia are usually named from the plants from which 

 their galls are obtained. The gall on Veronica cJuunadrys, 



mentioned at the beginning of this paper, is one of the 

 commonest ; it consists of an arrested terminal shoot with 

 closely overlapping leaves. Externally it is reddish in 

 colour and covered with grey hairs ; within is a padding 

 of hairs, and in the axil of each leaf a cell is formed con- 

 taining the orange larva of the gall-midge ' '. vtroiiica. 

 Whether any inquilines have ever been noticed in it or 

 not, we have not been able to ascertain, and the evidence 

 aflbrded by the white larvie is inconclusive, for Mr. F. 

 Binnie states that the larvse of C. tiifidii, which galls the 

 clover-leaf, are white when young but gradually change to 

 orange at maturity. But as the number of larv;^ in the 

 gall was larger than usual, the probability that the white 

 ones belonged to a difterent species from the orange ones 

 is considerable. Be this as it may, the gall in question, 

 according to Prof. Trail, is really a mite-gall, which is 

 taken possession of by the gall-midges ; and if this opinion 

 be correct, then our white and orange larvie, whether of 

 the same species or not, both partook of the eu;koo 

 character. The gaUs on the wild thyme are of a similar 

 description, and are tenanted by the orange larva^ of 

 C. tht/niu'ola. 



The reader who desires to pursue this subject will do 

 well to consult the article on galls in the " Encyclopsedia 

 Britannica"; Mr. Cameron's volumes in the Eiy Society's 

 "Proceedings " on the British Phytophagous Hymenoptera ; 

 Dr. Adlers recently translated " Essiy on Oak Galls " ; 

 and the articles of Prof. Trail before mentioned, to which 

 we have been indebted in the preparation of this paper. 



THE FACE OF THE SKY FOR OCTOBER. 



By Herbeet Sadler, F.R.A.S. 



SUNSPOTS and faculae are still prevalent on the 

 solar surface. The zodiacal light should be looked 

 for before sunrise. Conveniently observable 

 minima of Algol occur at lOh. 30m. p.m. on the 

 18th, and at 7h. 18m. p.m. on the 21st. 

 Mercm-y is not well situated for observation during 

 October, as through the whole of the month he never sets 

 much more than half an hour after the Sun. 



Venus is stiU visible as a morning star, but is not very 

 well placed for observation by the amateur, and her 

 apparent diameter is rapidly decreasing. She rises on the 

 1st at Ih. 32m. a.m., or one hour and a half before the 

 Sun, with a northern declination of 3° 36', and an 

 apparent diameter of lOi", Teo'''is o^ ^^^ ^^^'^ being 

 illuminated. On the- 7th she rises at 4h. .50m. a.m., or 

 Ih. 22m. before the Sun, with a northern declination of 

 0^ 39', and an apparent diameter of 10 '. On the 17th she 

 rises at oh. 22m. a.m., or Ih. 6m. before the Sun, with a 

 southern declination of 1° 19', and an apparent diameter 

 of 10'. On the 31st she rises at 6h. 6m. a.m., or about 

 three-quarters of an hour before the Sun, with a southern 

 declination of 11^ 1', and an apparent diameter of 9|", 

 J/gths of the disc being illuminated. During the month 

 she passes through nearly the whole of Virgo, being very 

 near tj Virginis on the 8th. 



Mars is an evening star, and is excellently situated 

 for observation, coming as he does into opposition with the 

 Sun on the 20th. He is at his least distance from the 

 earth (40,010,000 miles) on the 12th. On the 1st he rises 

 at 6h. 32m. p.m., or .52m. after sunset, with a northern 

 declination of 9^ 86', and an apparent diameter of 21-2', 

 the phase on the p Umb being only 5". On the 8th he 

 rises at 6h. p.m., or 38m. after sunset, with a northern 

 declination of 9^ 10', and an apparent diameter of 21-6 ', 

 the phase being imperceptible. On the loth he rises at 



