External Conditions and Manuring. 321 
ria generationis. The branching of the ears of Triticnm 
turgidum compositum (Vol. I, p. 125) and the carpello- 
mania of Papai'cr somniferum (Vol. I, p. 138) are to a 
very large extent dependent on external conditions. 
Double poppies become almost single under unfavorable 
conditions; I have observed this in Papaver somniferum 
nannin album in my own cultures. Again the double 
Saponaria officinalis plena seems to become single after 
transplantation, but subsequently to regain its double 
character. 1 The ordinary Saponaria officinalis often 
forms hexamerous flowers in this neighborhood. These 
were, however, more numerous in my cultures under 
good than under bad treatment. The studies of PEY- 
RITSCH on the influence of the cutting clown of wood- 
bands on peloric varieties has already been referred to 
( 21, p. 225). On a lime tree in the vicinity of Baarn 
pitchers are produced every year; but I always found 
them on the open sunny side and never in parts of the 
tree where the branches were shaded by neighboring 
trees. 
The color is also well known to be very dependent on 
external conditions. Achillea Mille folium rosea will only 
form its fine red inflorescences in a sunny position ; if 
this is shaded the color is pale or absent, as I have myself 
often observed. Inflorescences grown in the dark re- 
main quite white, even when they would otherwise have 
been red. The same is true of Begonia semperflorens 
atropurpurea Vernon, whose brown red foliage cannot, 
so to speak, stand the smallest amount of shadow. In 
this case I have succeeded in making some plants almost 
quite green by shading them during their youth. The 
1 MuNTiNG, Waarc Ocffcuhigcn dcr Plantm, 1671, p. 588. Also in 
my garden. 
