A HISTORY OF SCIENCE 



nature whereby when they are older their flowering 

 and fruit-giving state will be produced. 



" We see this force of nature, which collects several 

 leaves around an axis, produce a still closer union and 

 make these approximated, modified leaves still more 

 unrecognizable by joining them together either wholly 

 or partially. The bell-shaped or so-called one-petalled 

 calices represent these cloudy connected leaves, which, 

 being more or less indented from above, or divided, 

 plainly show their origin. 



"We can observe the transition from the calyx 

 to the corolla in more than one instance, for, al- 

 though the color of the calyx is still usually green, 

 and like the color of the leaves of the stalk, it 

 nevertheless often varies in one or another of its 

 parts at the tips, the margins, the back, or even 

 the inward side while the outer still remains on 

 green. 



" The relationship of the corolla to the leaves of the 

 stalk is shown in more than one way, since on the 

 stalks of some plants appear leaves which are already 

 more or less colored long before they approach inflo- 

 rescence; others are fully colored when near inflores- 

 cence. Nature also goes over at once to the corolla, 

 sometimes by skipping over the organs of the calyx, 

 and in such a case we likewise have an opportunity to 

 observe that leaves of the stalk become transformed 

 into petals. Thus on the stalk of tulips, for instance, 

 there sometimes appears an almost completely devel- 

 oped and colored petal. Even more remarkable is the 

 case when such a leaf, half green and half of it belong- 

 ing to the stalk, remains attached to the latter, while 



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