12 6 THE ORCHID REVIEW. 



D. X Schneiderianum, D. X Wiganiae, D. X Pitcherianum Rolfeae, D. 

 Harold, D. X Sybil magnificum, D. X chlorostele xanthocentrum, D. 

 Ainsworthii varieties splendidissimum and intertextum, D. X Rubens vai 

 magnificum, Virgil, Apollo, and album, and D. X melanodiscus, wi 

 its varieties Rainbow, and Clytie. Considerations of space prevent mc 

 than a mere list of names, but those who know the plants can picture th< 

 effect, when it is added that the plants are superbly cultivated. Other go 

 things included are flowers of Cymbidium Lowianum, C. X eburne 

 Lowianum, and a fine spike of Ada aurantiaca. 



CULTURE OF ORCHIDS IN LEAF-MOULD. 



The discussion as to leafsoilhas interested me greatly, and I have potted 

 my whole collection in it — the labour of getting and preparing fern root 

 was a burden not to be borne, while this material is no more trouble than 

 potting plants in ordinary soil. The midge, Sciara inconstans, which is 

 troublesome in European greenhouses, and specially mushroom caves, works 

 in the material to some extent, and bites the new roots, that is to say the 



The leaf soil in Orchid pots coming from England (Sander & Co.) seems 

 like veritable earth ; what I use is flaky, and full of fern and tree roots, 

 creeping among the half rotten leaves. I think these a very important part 

 of the material, as the attendant mycorhizal fungi in many cases are quite 

 certainly of species able to assist the Orchid roots, just as they do those of 

 the forest trees. 



I had magnificent success last autumn in starting hybrid Orchid seed on 

 this leaf soil, ground up in a sausage cutter, but the Sciara larva; bred in it by 

 myriads, and devoured thousands of hybrid seedlings in a night. I saved 

 about 800 by transplanting them to wire netting trays, with a thin layer 

 of the same material—which contains no midges or larva when fresh— but 

 they were again attacked. I tried subjecting the trays to an atmosphere of 

 carbonic acid gas for several hours, but it had no effect on the maggots. 

 Then I fumigated for fifteen minutes with strong carbon bisulphide vapor 

 and killed all the larvae. In a few hours the largest seedlings (one inch high) 

 turned black, and in three days all were dead— the smallest ones surviving 

 the longest. In a preliminary trial seeds just turning to green globes were 

 not killed. 



I am making some experiments with seeds in closed glass jars, oxygen 

 being supplied by the use of hydrogen dioxide, which does not injure 

 germinating Orchid seeds, even when used in quantity, in full commercial 

 strength (three per cent). So far (five weeks) the experiment is more or 



