bureau of plant industry. 275 



Crosses between northern and southern varieties of corn. — 

 In connection with the increased yields of first-generation hybrids 

 previously reported it has been found possible to utilize the more 

 highly bred northern strains in combination with southern varieties. 

 In the high-yielding northern varieties the husks do not afford suffi- 

 cient protection to the ears under conditions in Texas. Though in 

 most cases the yield is large, the high percentage of damaged ears 

 greatly reduces the value of the crop. In first-generation hybrids 

 between northern and Texas varieties it was found that the ears 

 were almost as well protected in the hybrids as in the pure Texas 

 varieties. 



Improved methods of making corn hybrids. — ^In determining the 

 value of first-generation hybrids large numbers of artificial pollina- 

 tions have been made, representing many different hybrid combina- 

 tions for testing under different conditions. In connection with this 

 work improved methods have been devised, so that much larger num- 

 bers of crosses can be made in the limited flowering period of the 

 corn plant. 



Corn plants that fail to produce pollen. — It has been found 

 that under certain conditions some well-bred varieties produce very 

 little viable pollen. The tassels appear normal, and the anthers are 

 well formed, but careful inspection discloses the fact that no pollen 

 is shed. It is important that this condition be guarded against in the 

 selection of seed corn, as its prevalence will result in poorly formed 

 ears and reduced production of grain. 



Cultural improvements in other tropical crops. — Several of the 

 most important tropical crop plants — cotton, coffee, cacao, the Cen- 

 tral American rubber tree, and the banana — have been found to pro- 

 duce two or more kinds of branches, distinct in their positions, func- 

 tions, and powers of propagation. A report has been published de- 

 scribing these specialized habits of growth and their application to 

 methods of culture and pruning. 



DBUG-PLANT, POISONOUS-PLANT, PHYSIOLOGICAIi, AND 

 FERMENTATION INVESTIGATIONS. 



The work of the past year has in a general way continued the lines 

 of investigation hitherto pursued, and the organization of the office 

 has continued practically unchanged, Dr. R. H. True, physiologist, 

 having general charge of the work. 



DRTJG-PLANT INVESTIGATIONS. 



As heretofore, the work has been conducted along two general 

 lines: (1) Field investigations, carried on in the various testing gar- 

 dens and with various cooperators of the office; and (2) laboratory 

 investigations, carried on chiefly in the laboratories at Washington, 



Arlington testing garden. — The garden on the experimental 

 farm at Arlington, Va., during the past year has been placed under 

 the direct charge of Dr. Walter Van Fleet, expert in plant breeding^ 

 who was formerly connected with the introduction work at Chico, 

 Cal. The work of the garden consists to a considerable extent in 

 growing under observation small plat cultures of a large number of 

 drug and related plants from foreign sources, in order to determine 

 their cultural requirements and value for introduction. 



