Oenothera Leptocarpa. 357 



they are covered with numerous small pits which tend to 

 alter the color of the leaf. 



The fruits are long and thin, and therefore quite dif- 

 ferent from those of O. rubrinervis. They seldom ripen 

 because the plant flowers so late. In November 1896 

 I measured the length and breadth of the first five ripe, 

 or at any rate full grown, fruits on a number of plants 

 of 0. leptocarpa which occupied two beds. I divided the 

 breadth by the length and employed the quotient as a 

 measure of the thickness. The values which I got were 

 quite definite ; the mean thickness lay between 1 5 and 1 7 

 whereas that of Lamarckiana ranges between 22 and 24. 

 Thus we see that the carpels of O. leptocarpa are about 

 % as thick as those of the parent species. 



The following are the values which I obtained : 



The culture A was from the seeds of the two lepto- 

 carpa mentioned on p. 262; B from an artificially self- 



