ORCHID CONFERENCE. 



25 



capsules are not only less perfect in our houses than they would be 

 in a state of nature, but they also require a longer time to arrive at 

 maturity, a circumstance that must tell against the progeny. 

 The cause of this is also climatic, chiefly of course the enormous 

 diminution of sunlight and sun heat. To make this clear, I will 

 adduce one illustration, and for that purpose I select the New Gra- 

 nadian cattleyas of the labiata group, because they are among the 

 best of subjects for the operations of the hybridist. These cat- 

 tleyas have their home chiefly in the ravines and valleys of the 

 Cordilleras, at elevations ranging from 2,000 to 5,000 feet above 

 sea level, and between the second and tenth parallels of north 

 latitude. The plants by being transferred from proximity to the 

 equator, where on clear days the sun darts his rays either per- 

 pendicularly upon the place in which they are growing, or at a 

 comparatively small angle to them, to a high latitude like ours, 

 where the smallest angle at which the sun's rays can fall upon our 

 houses is about 28 deg., and that only for a few days at mid- 

 summer, an angle which daily increases, till at midwinter it 

 reaches 75 deg., suffer an enormous diminution of solar light. Now 

 light, in passing through the atmosphere, even under the most 

 favorable circumstances, is subject to absorption, or is intercepted 

 by it, but the amount varies with the angle ; thus, it has been shown 

 that of a given quantity of light falling perpendicularly upon a given 

 point, one-fifth of it is absorbed or intercepted by the atmosphere ; 

 if it fall at an angle of 50 deg. more than one fourth is inter- 

 cepted, and at an angle of 75 deg. fully one-half. Hence, in the 

 winter months, even when the days are clear and bright, we can 

 get no more than five-eighths (a little more than one-half) of the 

 solar light these New Granadian cattleyas receive in their native 

 country, on the assumption that other circumstances remain the 

 same. It is quite evident, then, at what a disadvantage we are 

 placed, as regards the ripening of capsules of Orchids whose 

 native home is near the equator, to say nothing of local 

 difficulties, such as the smoky atmosphere and fogs of London. 



It is not unreasonable to infer, in the absence of more 

 accurate knowledge obtained by direct observation, that the 

 capsules of the New Granadian cattleyas require but a short 

 period to attain maturity in their native country, and that this 

 period extends only over the two or three months of what is 

 there called the dry season, but which in that region is subject 

 to frequent showers. In our houses, the time required for 



