THE ORCHID REVIEW. 325 
due supply of manure is essential to their well-being. There is a danger in 
giving too gross a diet. You may easily destroy the plants by an excess 
of manure in any form, but the plants will certainly deteriorate and ultimately 
die with too little. How can nitrogen, the essential element of all manures, 
be supplied safely, and supplied in sufficient quantities to get the most 
vigorous growth? That is the question to be answered. I believe all the 
most successful growers know this necessity; many have their secrets, 
which they do not publish to the world, others tell all they know, and their 
advice is disregarded. 
I remember, many years ago, a French Orchid grower boasted that he 
had a secret which enabled him to excel his brother horticulturists. The 
boast made him very unpopular, and deservedly, but he never divulged his 
secret. I do not, of course, know what it was, but, like most secrets, I 
suspect it was something well known, but disregarded. I can even guess 
what it was, and I shall now explain the method which he most probably 
believed to be known only to himself. Although in reality it is well known, 
only very few practise it or recognise its utility. It consists simply in 
placing a few pieces of carbonate of ammonia on the piers supporting the 
pipes, not on the hot water pipes themselves, but near them. The 
carbonate ofammonia slowly evaporates, and is absorbed by the moisture 
in the pots or on the leaves of the plants. I use about a pound of carbonate 
of ammonia in a year in this way, and I believe if I used twice as much in my 
small house, 2oft. by 12ft., I should not exceed the requirements of the 
plants. I am quite convinced of its utility, not only on scientific grounds, 
but from observation. Whenever I have neglected it, the flowers are less 
developed, poorer in colour and size, and the plants are less vigorous. 
The manner in which the roots of the plants cling to charcoal, which has 
an especial tendency to absorb the vapour of ammonia, suggests the 
advantage of feeding the plants in this manner. The quantity of ammonia 
I use—generally one or two fragments the size of a walnut or somewhat 
larger—does not produce a perceptible odour of ammonia, but it is enough 
to give the plants the extra stimulus they require to grow them vigorously. 
It was also pointed out that common salt might be applied as an aérial 
manure, as it evaporates in the presence of moisture, and certain Orchids 
which grow near the sea were believed to like it. Count de Buysson had 
adopted the practice of syringing his plants once or twice a week, or more 
often when growing vigorously, with a water containing guano or carbonate 
of ammonia, at the rate of I5 grains to a litre (13 pints) of water, and the 
writer had used it in smaller quantities, and also for watering Cypripediums, 
with beneficial results. The guano was placed in a muslin bag and soaked 
in rain-water for 24 hours. We should much like to hear the results of 
other experiments of this kind. 
