JANUARY, 1912.] THE ORCHID REVIEW. 7 
CYPRIPEDES ON LIMESTONE, 
I am pleased to find that my little paper has induced an observer to record 
facts. Mr. Lyon is far too generous in his praise. He is probably unable 
to consult a complete set of the Orchid Review, and, therefore, does not 
realise that, to a very large extent, I merely collected the observations of 
others. I am particularly glad that Mr. Lyon records a difference between 
the growth of plants in limestone and those in mortar, as it is further 
evidence of the need of attention to apparently trifling differences. I can- 
not, I am afraid, agree with Mr. Lyon when he says, “ how little after all 
we can utilise a knowledge of plant environment.” We cannot put a whole 
limestone cliff in an Orchid house, and we do not always get such a 
generous allowance of sunshine as Mr. Lyon describes, but we can construct 
crevices in limestone suitable for plants to root in, and we can make more 
use, if need be, of the sunshine we have. There should be no great difficulty 
in reproducing, at any rate partially, the conditions under which Cypri- 
pedium philippinense and C. Haynaldianum grow naturally, without 
damaging the plants. — I believe that with very little trouble we could come 
much nearer to natural conditions with benefit to the plants. All growers of 
Cypripedes should be grateful to Mr. Lyon for the facts he has recorded, 
but we are still short of information, and I hope he will be able to give 
us some more. 
If I had been able to continue Orchid growing I intended, as an advance 
towards natural conditions, to try the effect of an artificial breeze, produced 
by a rotary fan, on the plants. The house would generally have to be shut 
up while the fan was at work in case cold draughts were produced by 
drawing in air through the ventilators. There are probably few Orchids 
that live in a still and stagnant atmosphere naturally, and as a breeze sup- 
plies the plants with passive exercise by moving the leaves it must have an 
effect ; probably a beneficial one. 
Many Orchids, too, come from districts where there are frequent thunder- 
storms. Every flash of lightning produces a quantity of various oxides of 
nitrogen. These oxides when nearly formed are in an extremely active 
state, and ready to form compounds with various matters with which they 
come in contact. The same oxides (incorrectly called ozone) could be 
produced in an Orchid house by a suitable electrical machine, such as a 
Wimshurst. A house might be shut up for half an hour while the machine 
produced a miniature thunderstorm. If the thunderstorm were followed 
up by a very fine spray, continued for some time, a large part of these 
nitrogen oxides would be dissolved by the spray and carried down on to the 
plants, probably with nourishing and other beneficial effects. I wanted to 
try this experiment three years ago but had not the time. Of course these 
