ON HEREDITY 
crowded for room. Plants which grow high do so 
usually because, at some stage in their existence, 
they have had to grow high to get the sun and the 
air which they need. Low-lying plants, like the 
pumpkin for example, give evidence that they have 
always enjoyed plenty of space in which to spread 
out. 
“The bear of your story may have slipped 
away, unknown to its keepers, and seen another 
bear fish for salmon; but if these tendencies and 
traits, and if the ability to perform the feats 
necessary for existence are not passed down from 
mother to son—if they do not come down through 
the line of ancestry, if all of the old environments 
of the past have not accumulated into trans- 
missible heredity, what enables that sweet pea to 
twine around the stake?” 
“A closer observation of the sweet pea will 
show us that its tendrils are really modified leaves, 
produced, like the spines of the cactus, by ages of 
environment which, added up, combine to make 
heredity; and that their actual sensitiveness to 
touch is so highly developed that they almost 
instantly encircle and hold fast to any suitable 
support within their reach. 
“It would be interesting to take a motion 
picture of a sweet pea as it grows, as similar 
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