139 



the dead insects. Weaker solutions were proportionately less elective. . . 



Tobacco Water. — ' Steep 5 lbs of refuse tobacco (stems, <fec.) in 3 

 gallons of water for three hours. Strain the decoction and add 

 sufficient water to make 7 gallons/ This mixture will kill soft bodied 

 species that are unprotected by a covering scale, such as Leeanium 

 viiide, Pulvinaria psidii, and Dactylopius citri. It has little or no effect 

 against the Diaspidinae. 



Lime Water. — -In the early days of the 'green coffee bug' I used a 

 very thin wash of quick lime and water. The mixture is inconvenient 

 or difficult to apply as a spray, as it quickly clogs the nozzles and 

 valves of the machine. I applied it with large brushes to the affected 

 coffee foliage, and it was certainly fatal to every insect with which it 

 came in contact. The bugs turned from green to a bright orange colour 

 within five minutes of the application. But many individuals neces- 

 sarily escaped, and the benefit was only temporary. No damage to 

 the trees was observed, but the lime had such a caustic effect upon the 

 hands and arms of the coolies employed in the work that it had to be 

 discontinued 



Soot is an article that has been greatly over-rated as an insecticide 

 and wood ashes may fall under the same category. The substances are, 

 doubtless, useful in dealing with slugs and snails, their astringent and 

 absorptive properties acting upon the mucous surface of such animals ; 

 but, when applied to dry insects, such as caterpillars and scale bugs, 

 they fail to adhere, or, when adhering, to act in any way prejudicial to 

 the insect. 



Lime, when applied dry, has little or no effect, unless there happen 

 to be moisture upon the insects. Even then its action will be very par- 

 tial and unsatisfactory. 



Powdered sulphur is also quite useless against scale insects. 



Many other substances have been made the subjects of experiment; 

 but, as they are either far too costly or otherwise impracticable, it is 

 useless to enumerate them. 



SEEDLESS GRAPES. 



Herr Muller-Thurgau attributes the absence of seeds in many 

 varieties of grapes sold in the markets to two causes — functional ineffi- 

 ciency of the pollen and of the ovule. In some varieties the pollen- 

 grains are well developed, but either the pollen-tubes do not reach the 

 ovules or the ovules are themselves incapable of impregnation. To this 

 class belong the sultana- raisins and the currants of commerce. In other 

 varieties, on the other hand, the ovules are perfect and capable of im- 

 pregnation, but the pollen grains are functionally defective ; either the 

 polien-tubes do not germinate on the stigma, or they are incapable of 

 impregnating the ovules. Grapes which do not contain seeds are 

 smaller than those which do. — (Landwirthsch Jahrb. d. Schweiz, 1898.) 

 Pharmaceutical Journal. 



