618 



SCIENCE 



[N. S. Vol. XL, No. 1035 



at but a fraction of the cost of tea and 

 supplies the same alkaloid in a more easily 

 soluble form. Both contain thein, the ac- 

 tive principle in "the cups that cheer but 

 not inebriate." Sturtevant names twelve 

 plants the leaves of which are used in dif- 

 ferent parts of the world to adulterate or 

 in place of tea. We have but just acquired 

 the use of cocoa and chocolate from the 

 natives of our American tropics and of 

 coeacola from the negroes of Africa, and it 

 is not unlikely that we shall find other 

 similar stimulants. For drinkers of more 

 ardent beverages, if King Alcohol con- 

 tinues to reign, there is an abundance, the 

 diversity and cheapness of which probably 

 will ever as now be regulated by taste and 

 -taxes. 



Time prevents my naming other valuable 

 Sorei'gJi plants that deserve to be tried in 

 ■&vlt agriculture. It is fortunate for Amer- 

 ican farming that men from the United 

 States Department of Agriculture are now 

 searching everywhere for new material. 

 Saul went in search of asses and came back 

 with a crown. So these men sent to foreign 

 countries for material, possibly common- 

 place enough, are bringing back treasures 

 the value of which in many cases will be 

 incalculable. Introduction of seeds and 

 plants for the nation is work to which the 

 Institutions represented here should lend 

 aid in every way possible. 



The last of the three means of developing 

 plants for food, and as I believe the most 

 important, is by using either foreign spe- 

 cies or wild native species to hybridize with 

 established crop-plants. It needs but a 

 brief statement of what has been accom- 

 plished in increasing hardiness, productive- 

 ness, disease resistance, adaptability to 

 soil and other essentials of standard crop- 

 plants, to show that through hybridization 

 of related species we have probably the 

 best means of augmenting our diet. Let 



us glance at a few recent accomplishments 

 of hybridization, noting chiefly results with 

 horticultural plants. 



Downing in 1872 described 286 varieties 

 of 4 species of plums. In the 40 years that 

 have elapsed the number has increased to 

 1.937 varieties representing 16 species. 

 Now the significant thing is that whereas 

 Downing 's plums were pure-bred species, 

 155 of the present cultivated plum flora 

 are hybrids between species. Downing 

 could recommend plums for only a few 

 favored regions. Some kind of plum can 

 be grown now in every agricultural region 

 in North America. Even more remarkable 

 is the part hybrids have played in the evo- 

 lution of American grapes. At the begin- 

 ning of the nineteenth century, the grape 

 could not be called a cultivated crop on 

 this continent. Now there are 16 species 

 and 1,194 varieties, the most significant fact 

 being that 790 or three fourths of the total 

 number are hybrids. The grape through 

 hybridization has become one of the com- 

 monest cultivated plants. The genus Rubus 

 promises to attract and distract horticul- 

 turists next. As nearly as I can make out 

 there are about. 60 species of Rubus in 

 North America. In the two completed 

 parts of Pocke's "Species Ruborum," 273 

 species are described. Raspberries, black- 

 berries, dewberries and their like hybridize 

 freely and we already have in the logan- 

 berry, the purple-cane raspberry, the wine- 

 berry and in the blackberry-dewberry 

 crosses valuable fruits. If any consider- 

 able number of Focke's several hundred 

 species can be similarly mixed and amal- 

 gamated, the genus Rubus will be one of 

 the most valuable groups of fruits. 



The speaker is studying cultivated 

 cherries. When the work began a few 

 years ago about a score of species were in 

 sight. Koehne, a recent botanical monog- 

 rapher of the sub-genus Cerasus, to which 



