78 



MEMORANDA. 



used in similar quantities. The leaves and branches which were thus dressed 

 with oil perished in a few days ; those to which naphtha and whisky were 

 applied were apparently uninjured. Oil destroys both scale and plants; 

 whisky and naphtha destroy mealy bug while in an active state, but has no in- 

 fluence over the eggs of the insect. — James Donald. 



Spirit (f Wine, to destroy scale, mealy bug, &c., has been tried. The 

 spirits were applied to the plants with a camel-hair brush. In twelve hours 

 afterwards the part where the spirits had been applied became a brown spot, 

 and if they were diluted with water so as not to injure the plant they had no 

 effect on the insects. This mode of destroying insects cannot be applied 

 with safety ; if strong enough to destroy them, it also destroys the plants. — 

 J^MEs Donald. 



Sulphuretted Hydrogen Gas. — Some plants were put into a close box in 

 which the gas was given off. Ten plants of different sorts were subjected to 

 this treatment; some were dry when put in, others wet, but all were well 

 syringed with soapsuds immediately after they were taken out. It was found 

 by experiment that six hours produced the same effect as forty-eight. In 

 every case the insects were destroyed, but the following table shows that this 

 process is injurious to the plants. 



I Time in 

 the Box. 



Pelargonium . . . 



Ditto .... 



Dodonaea triquetra . 



Echiuocactus . . 



Primula sinensis . . 

 Ditto .... 



Bletia sp 



Jasminum Sambac . 

 Mammillaria discolor 

 Caniia indica . . . 

 Opuntia ferox . . 

 Euphorbia splendens 



Dormant 

 Growin" 



Dry 

 Wet 

 Dry 



Wet 

 Drv 



Hours. 



48 



12-1 

 12> 



12^ 



Dead when taken out 



Died in three weeks afterwards 

 No l)ad effect* could be seen for a 



few weeks, then It gradually 



rotted off 

 Dead when taken out 



Very much injured 



Dead when taken out 



Meyer's Composition. — A Composition for destroying cockroaches and 

 other insects was sent to the Garden by Mr. G. H. Meyer, its inventor. The 

 substance in every respect resembled pounded gum arable. It was, accord- 

 ing to the directions of Mr. Meyer, laid down at night in dry places which 

 the insects frequented, and taken up in the morning. It is impossible to say 

 whether or not any insects tasted it. When exposed to a humid atmosphere, 

 it became like gum ; moths, beetles, woodlice, ants, &c., &c., were found to 

 live for days in a vial beside it. The experiment was a failure. — James 

 Donald. 



Hereman's Dilutium. — A small vial containing a liquid " Vegetable 

 Dilutium," for destroying mealy bug and other insects, having been sent to 

 the Garden by Mr. S. Hereman, its iuventor, the following trials were made 

 with it. According to his directions, the liquid was applied to the plants 

 with a camel-hair briish, and when thus dressed they were well syringed 

 with pure water. The plants on which it was tried were Berberis tenuifolia, 

 Olea fragrans, Epidendrum cochleatum, and Mammillaria gracilis. In a 

 few days after its application Mammillaria gracilis died, and all the other 

 plants were more or less injured. In every case the mealy bug was killed, 

 and also many of the white scale, but apparently none of their eggs, as they 

 appeared as numerous as ever in a few weeks afterwards. — James Donald. 



