56 



malic acid. Thus the voung branches of white mulberry are defended 

 bv their acidity irom' Aulacaspis {Diaspis) petitago7ia ; young citrus 

 trees from Pseudococcus citri and Chrysomjjhalus dictyospermi ; young 

 fig-trees from Ceroplastes rusci ; young olives from Saissetia oleae and 

 Filippia (Philippia) oleae ; citrus and other fruit-trees from 

 caterpillars; olives from Dacus oleae; grapes from Cryptoblabes 

 gnidiella {Alhinia wokiana) and the vines from Phylloxera. 



Fauchere ( — ). La Sericiculture d Madagascar, [Silkworm Culture 

 in Madagascar.] — C. R. Hebdoni. Acad. Sciences, Paris, clxv, no. 20, 

 12th November 1917, pp. 676-677. 



The varieties of Bombyx {Sericarki) man introduced into Madagascar 

 from south Europe were all monovoltine, producing one generation a 

 vear, but on becoming acclimatised at the*end of about two years they 

 produced six generations. So far from their silk being inferior in 

 quahty and quantity to that of the monovoltine forms, it proved to be 

 of first rate quality. Again, while the eggs of the original species 

 would hatch only after hibernation, those of the polyvoltine forms 

 hatched regularly 12 or 13 days after being laid. 



As in Europe, silkworms in Madagascar are attacked by several 

 diseases, especially pebrine, rendered more serious in the tropics by the 

 continuous breeding of the insects throughout the year and ihe 

 carelessness of their native cultivators. 



In order to obtain strains of non-infected eggs an improved form of 

 the cellular egg-tray used in Europe was employed, thus preventing 

 the usual mixing of the eggs, so fatal in ordinary practice, 



Grassi (B.) & Topi (M.). The Number of Races of Vine Phylloxera.— 

 — Mthly. Bull. Agnc. Intell. & PI. Dis., Rome, viii, no. 9, 

 September 1917, pp. 1322-1327. [Abstract from Rendiconti Sedute 

 R. Accad. Lincei, Classe di Scienze fisiche, matematiche e naturali, 

 Rome, 5th Ser., 1st half-year 1917, xxvi, no, 5, pp. 265-273.] 

 [Received 10th December 1917.] 



The authors of this paper, desiring to solve the problem of the 

 different ways in which Phylloxera spreads in Italy, undei*took 

 investigations on a gall-producing form that had developed on leaves 

 of the Clinton variety of vine at Arizzano. The results showed that 

 with galls taken from that variety it was not possible to infect either 

 the leaves or roots of the various American vines, though these can be 

 infected with galls and nodules from material taken from other vines 

 in other districts. Galls are apparently most easily produced on 

 varieties identical with or similar to those already infected. The authors 

 suggest as a likely hypothesis that, in order to continue the cycle 

 to the winter egg, the winged insects oviposit on the leaves or 

 bark of vines near those on the roots of which they have develo]3ed, 

 and that the passage of the gallicolae from one vine to another, 

 and consequently the formation of galls, is regulated by conditions 

 hitherto unknown. This hypothesis was confirmed in another 

 series of tests and observations. The winged form, which contri- 

 butes to the dispersal of the insect, develops comparatively rapidly 

 on the roots of European vines, while the gall-producing form does 



