352 BOTANICAL GAZETTE [may 
chlamydeal flowers I have ascribed much influence to insect- 
pollination, yet I must contend against the opinion that the 
formation of petaloid structures has been induced by insect- 
pollination. The appearance of these structures in various 
and widely separate series can at first only have been condi- 
tioned upon external influences. In countless culture plants we 
see that by supplying richer nutrient materials and more light 
the formation of petaloid structures notably increases, and that 
sepals and stamens become petaloid. But it is to be conceded 
that insect visits may contribute to the fixation of such charac- 
ters when once acquired, but they alone could not accomplish 
this were the physiological causes of color supply not perma- 
nently furnished to the succeeding generations. The develop- 
ment of color material in the floral phyllomes may also be 
retarded by its transference to the subtending bracts or to genes 
more favored flowers in the inflorescence. In the Spathiflore 
the development of the flowers remains in the background, 
owing to the manifold capabilities of the spathe, while the a 
loid bracts of Dalechampia in the Euphorbiacee produce the 
same result. The inner flowers in the inflorescence of sn 
gea are retarded by the strong petaloid development “ rd 
periphery. On the other hand, insect-pollination ‘a deci c “i 
instrumental in the reduction of flowers, more than in the =p 
petaloid development of particular perianth-whorls. F = he 
quite clear that when the insects continually prefer in sr a ni 
those stamens or carpels most conveniently situated, gg . 
used must gradually become functionless. Here it ia ve 
question of production of certain materials, as 1n the et already 
petaloid perianth, but only of restriction or suppression © : 
existing structures at the expense of other more 
Among the monocotyledons the Scitamine pene goral 
sperme surpass all others in the prod . 
parts, in the prevalence of zygomorphy, 
‘the andreeceum. In the dicotyledons these co 
in a great number of series. 
nditions appe** 
BERLIN. 
