395 



are monophagoiis, which fact probably depends upon physiological 

 conditions, and therefore the smallest change in the juices of the plants 

 may liave a profound effect upon them. The author began his experi- 

 ments as long ago as 1903, without being aware of the work of 

 Mokrzecki, Shevirev and Berlese. Latterly, he has worked out a 

 simple method of introducing solutions into plants ; a rubber tube 

 is placed on tlie cut surface and is connected with an ordinary Esmarch 

 cup, filled witli the solution, suspended on the tree ; the fluid penetrates 

 into the cut by the suction produced by the transpiration of the tree. 

 In this way, the author succeeded i]i ijitroducing enormous volumes 

 of li(^uid into plants. Thus, in 29 hours, 10| litres of a solution of 

 arsenic acid in water (1 : 500) were introduced into an apple tree. 

 The speed of the absorption depends directly on the diameter of the 

 branch experimented on and on the degree of rapidity with which 

 the leaves evaporate the li([uid ; it also varies with the species 

 of plant and with the liquid used. Colloids are hardly absorbed 

 at all and crystalloids vary greatly in their rate of absorption. Salts 

 of alkali metals, especially chorides, are the most rapidly absorbed, 

 those of alkali earths less rapidly. Sulphates are absorbed more 

 slowly than chlorides, while carbonates are absorbed the least. In 

 order to increase the speed of the entry of liquids into plants, 

 introduction under increased pressure was tried. It appeared that 

 fruit trees and vine-stocks stand, without injury, the introduction 

 of liquids under a pressure of up to eight atmospheres. Experiments 

 were made on destroying Eriosoma (Schizoneura) lanigerum by means 

 of introducing barium chloride (1 : 350) and potassium arsenite (1 : 350) 

 into apple trees through the roots. In 1903, the solutions were intro- 

 duced o]i 29th July and the examination of the trees on 7th August 

 showed that the white covering of the aphids had disappeared, 

 while the aphids themselves had practically perished. After another 

 introduction on 7th August of IGgrm. barium chloride in 800 cc. of 

 water the lice had totally disappeared on 3rd September. The experi- 

 ments of 1909 produced a decrease in the number of aphids, while their 

 total disappearance was effected only in 1910. The experiments of 

 1912 on four trees resulted in the total destruction of the pest on one 

 eight-year old tree, which received one-third grm. of barium chloride 

 (1 : 1,000). For trees 20 years old, a dose of up to 1 grm. of barium 

 chloride proved insufficient. How long the effect of the insecticide 

 lasts is uncertain, but it is not limited to one year. Potassium arsenite 

 and arsenic acid proved to be very poisonous to trees, barium chloride 

 less so. Experiments in thus protecting vine-stocks from Phi/IJoxem, 

 have not yet given any definite results. 



Krassilstchik (I. M.). OmeT-b o fltflrejibHOCTM Bio-3HTOMonorM- 

 MeCHOM CraHl^iM BT* 1914 rofly. [Report on the work of the Bio- 

 Entomological Station (of Bessarabia) during 19iJ:.] Published 

 by the Zemstvoof the govt, of Bessarabia. Kishinev, 1915,49 pp. 



Though Clysia ambiguella, Hb., occurred in large numbers in 

 Bessarabia in 1912 and 1913, causing serious damage in 1914, 

 it was Httle in evidence, probably owing to the vineyards being 

 largely affected by mildew {Plasmopora viticora) which attacked 



