106 THE ORCHID REVIEW. 
practice occasionally throwing manure-water about the floors at times when 
the roots are most active, and others throw down a mixture of lime and soot, 
which generates ammonia, and thus the air is charged both with ammonia 
and moisture, which, being absorbed by the roots, produces a more luxuriant 
growth. Mr. Cypher, of Cheltenham, sprinkles the floors with manure- 
water twice a week during the summer months, and also uses trough pipes, 
in which a little manure-water and soot is occasionally placed, and it is 
well known that he is one of the most successful growers of Dendrobiums 
in the country. Mr. Wrigley, of Bury, uses a mixture of lime and soot, and 
affirms that beneficial results are seen in the deeper green of the foliage, and 
certainly many of his plants are pictures of health. This seems to me 
perfectly rational treatment, for it is certain that ammonia as well as 
moisture is present in the air where Orchids grow naturally, and the very 
existence of aerial roots suggests this, otherwise they would not have 
departed from their ancestral habit of growing in the soil. It is clearly an 
adaptation for obtaining the necessary food in the modified conditions under 
which they live. 
Some Orchids have both terrestrial and aerial roots, as Vanilla, and 
evidently both are concerned in obtaining the food supply of the plant. A 
somewhat similar modification is seen in certain Catasetums, Gongoras, and 
others, where numerous roots grow perfectly erect from the compost, giving 
the plant quite a curious appearance. There are examples of the former in 
the Orchid houses here, and Mr. Hart, of Trinidad, has published some 
interesting observations on the latter. “Gongoras,” he observes, ‘ like 
ts are examined closely it will 
at are below the surface of the 
mud, there are countless thousands of tips that are exactly perpendicular. 
That these roots perform some function, important both to Orchids and to 
mangroves, &c., is clearly apparent, as where they are most abundant the 
plant and the tree is most vigorous and in the most robust health. But 
what that function is exactly is not clear to us, but the feature is such a 
notable one that it is deserving of further close enquiry.” 
