H. BOTANY AND HOliTICULTURE. 351 



surface of the nut glabrous or (rarely) pubescent ; the fruit 

 generally matures in the first year. 



"The Black oaks have dark, furrowed bark, brittle and por- 

 ous wood, styles long, and spreading or recurved, abortive 

 ovules always near the tip of the perfect seed. The leaves 

 and their lobes are bristle-pointed, at least in youth ; lobes 

 and teeth acute ; teeth sometimes spinous. Their stamens 

 are usually less numerous, the scales of their cup membrana- 

 ceous, the inner surface of their nut always tomentose; the 

 fruit generally matures in the second year." 



HETEROMOEPHISM I2T EPIG^A. 



Fruit is seldom met with in Epigoea rejyens^ or common 

 Mayflower. In the American Journal of Science l*i-ofessor 

 Asa Gray calls attention to the heteromorphic states of the 

 flowers as follows : 



"There are four kinds of flowers: the first ^vf'ith long style 

 and perfect stigma ; the second^ with perfect stigma likewise, 

 but shorter style. Both have more or less abortive anthers 

 lower than the stisfmas. These two forms amounted togfetlier 

 to less than twenty per cent, of a large number of specimens 

 from one locality in Maine. In the third form, with longer 

 style than No. 1, but imperfect stigma, the anthers abound 

 with pollen, and are dehiscent at or a little before the open- 

 ing of the corolla. The fourth has a shorter style, with the 

 imperfect stigma as low as the base of the five longer anthers, 

 otherwise as in No. 3. The flowers oi Epigma may therefore 

 be classified into two kinds, each Avith two modifications: 

 the two main kinds characterized by the nature and perfec- 

 tion of the stigma, along with more or less abortion of the 

 stamens ; their modifications by the length of the style. 

 The first is leading to dicecism, the second points to dimor- 

 phism, a singular fact among Ericaceae^ which usually secure 

 intercrossing by dichogamy, i, e., by developing the anthers 

 before or after the stigma." 



GROUPING OF ZOOSPORES IN WATER. 



When zoospores are swimming about in water, they fre- 

 quently collect in masses of different shapes, but generally 

 of some symmetrical form. This was supposed to be owing 

 to the action of the light ; but Sachs shows that it has nothing 



