H. BOTANY AND HORTICULTUEE. 375 



structure. These two processes go on at different rates in 

 light and darkness, and, by a proper consideration of them, 

 the discrepancies that have hitherto been noticed by accur- 

 ate observers seem to disappear. Besides certain observa- 

 tions made upon the leaves, Draper adduces an interesting 

 fact, Avhich lends support to the opinion that the process of 

 growth in seedlings developed in the dark is very similar 

 to that occurrinof to those 2:rown in the lio-ht. It is well 

 known that many plants so poison the soil that the same 

 plants can not be made to grow therein nntil the poisonous 

 excretions from the roots of the first crop have been destroyed 

 by oxidation. In the case of pease, this poisoning of the soil 

 takes place in a very marked manner, no matter whether the 

 pease have grown in the dark or in the light. In general, 

 Draper concludes that the whole history of the plant, from 

 the time the seed is planted to its death, is a continuous 

 story of oxidation, except when sunlight is falling on the 

 leaves. The seed is put into the ground, and during germi- 

 nation oxygen is absorbed and carbonic acid exhaled. If the 

 seedling be kept in the dark, oxygen is never exhaled, car- 

 bonic acid is, and the plant not only grows, but all visible 

 structures, except flowers, are formed in a rudimentary con- 

 dition. The growth during the night-time is attended by the 

 evolution of carbonic acid, while during the day-time the bark 

 of the stem and branches is throwing off carbonic acid. 12 

 A, 1873, 373. 



SPECIES OF PLANTS OF THE UNITED STATES DESCRIBED IX 



18V3. 



The following new species and genera of phaenogamic 

 plants and ferns, from within the limits of the United States, 

 have been published during 1873: 



Aquilegia chrysantha. Geay, Proc. Amer. Acad., p. 8, 621. 

 New Mexico. 



WisUzenia Pcdmeri. Gray, 1. c, 622. Lower Colorado 

 Valley. 



Polygala suhspinosa, Watson, Amer. Naturalist, p. 7, 299. 

 Arizona and Nevada. 



Franlcenia Jamesii^ Torre y. Gray, 1. c, 622. 



Brewerina siiffrutescens^ new genus and species. Gray, 

 1. c, 620. California. 



