FLORAL DEMONSTRATION. 
137 
were derived, while Mr. Bateson was of opinion that C. lanatahsbd 
something to do with the original parentage. There was no 
doubt that most plants soon begin to vary, even without crossing, 
under cultivation, and numerous varieties can be established 
when the process of selecting seed from certain flowers is adopted. 
He suggested that both opinions might possibly be right, for 
an analogous case would seem to be presented by the Pansy. 
This was a favourite'garden flower in 1725; but in about the second 
or third decade of this century it is believed to have been crossed 
with Viola altaica, V. grandiflora, &c. At the present day it 
would be quite impossible to detect and distinguish the true un- 
crossed descendants of V. tricolor from those of hybrid origin. 
So, possibly, may it be with Cinerarias. 
Professor Henslow next drew attention to some Cactaceous 
plants exhibited by Mr. Cannell and Mr. Ludford, such as 
Pilocereus senilis, Echinocactus cornigcra, Mamillarias, and 
compared their forms with some fleshy- stemmed species of 
Euphorbia. He pointed out the great resemblance in general 
appearance between these plants, although they belonged to 
entirely different families. The reason for this resemblance was 
that the plants which were natives of arid deserts adapted them- 
selves to their surroundings by assuming the same vegetative 
structures. Thus in the deserts near Cairo all plants have a 
bluish appearance, caused by hairiness, or else they are thick and 
fleshy-stemmed. The cuticle is hard and thick, and prevents 
the transpiration of water from the cells. 
BrodlcEa volubilis, a Liliaceous plant from Messrs. Wallace & 
Co.'s (Colchester) collection, was the next plant called attention 
to by the lecturer. He pointed out that its peculiarity lay in 
the fact that the long flower-stems had a climbing habit, twisting 
round artificial supports by aid of the motion called ^' circum- 
nutation." This again was simply an adaptation to circum- 
stances. Plants which grew in dense shady forests often pro- 
duced long stems by which they pulled themselves up to the 
light. Many such plants have a climbing habit, when allied 
species growing in the open assume a short and more or less 
shrubby habit, as in some species of Convolvulus growing in 
deserts which are stunted woody little shrubs. 
Calochortus (Cyclobothra) pulchra and C. venustus, from the 
same firm. The Cyclobothra section of this genus differs con- 
