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Jan 31/72/

Natural Selection & Variation

à Bears on Duval-Jouve on difference of cells —

Plants are certainly adapted to different climates, degrees of moisture — light — they absorb different elements from the soil — they can compete with different plants — go to different depths in soil; grow to different heights &c &c — They secrete diverse chemical elements some apparently serving as a defense to attacks from various enemies — Therefore there must be great difference in their contributions, & it seems incredible to me that these differences shd not lead directly & indirectly through laws of growth to external changes — though we have no evidence on this head — except we see what a wonderful effect the poison of diverse gall-forming insects & fungi have on the growth of tissues.

It is incredible that there shd not be far more adaptation in plants than in the few cases which we can see, as in shape of flower for fertilisation — of seed for dispersal — for Climbing &c ↘

[178v]

Is it credible that one [illeg] plant cd be converted into a tree without all the parts being more or less modified by laws of growth?—

[Joseph Duval-Jouve (1810-1883), French botanist.]