332 THE AMERICAN MONTHLY [Nov., 



The Fruits of the Order Ranunculaceae. 



By KARIv M. WIEGAND, 

 cornell university, ithaca, n. y. 



All abstract of a paper read before the American Microscopical Society, 

 August, 1894. 



The importance of characters drawn from the fruit in 

 the limitation of the larger groups has not been fully 

 recognized. Only the gross anatomy or external features 

 have been used, while the minute structure of the seed 

 remains yet obscure in most of our natural orders. 



Actual variation in organisms is probably augmented 

 by changes in environment and modified by natural se- 

 lection. It follows, therefore, that those parts farthest 

 removed from external influences are the most constant, 

 because they are not required to adapt themselves to 

 any new conditions, and they have long ago become al- 

 most as well fitted to perform their function as possible. 

 Moreover, the tendency is when organs have remained 

 unvaried for a long time to loose the power to vary. It 

 is assumed that the function of the organ is also constant, 

 which, is not always the case. 



The features of a plant most subject to variation 

 through changes in environment are habit, foliage, and 

 parts of the flower. The latter should include the floral 

 envelopes, surface of the seed, and everything having di- 

 rectly to do with pollination and dissemination. The 

 two most constant series of organs in a plant seem to 

 be, first ; those connected with nutrition including the in- 

 ternal anatomy, and subject to changes in the soil and 

 atmosphere. Secondly, those organs connected directly 

 with reproduction, especially the internal parts of the 

 seed. These are little afl"ected by environment, and are 

 practically constant if reproduction itself is constant. 

 But there is no essential difl'erence between the way in 

 which new plants are produced in the Polypetalffi and 

 Monocotyledons. Practically the same method is used 



