ALFALFA SEED PRODUCTION". 



21 



flowers that tripped first were on the outside of thef plant. The 

 screen was replaced, so that insects had no access to the flowers, nor 

 was the screen again removed until the seed was mature. 



It was estimated that more than one-half of the flowers counted 

 on each raceme thus became self-tripped before the screen was re- 

 placed. None were artificially tripped, as extreme care was taken. 

 The results are presented in Table XII. 



No flowers already tripped were noticed when the screen was first 

 removed. Apparently the tripping was induced when the screen 

 was removed by the increased transpiration from the turgid flowers. 

 Certainly no insect agency was involved. The total number of pods 

 produced was 23.7 per cent of the total number of flowers counted 

 and tagged. 



Table XII. — Results obtained with a single alfalfa plant screened from insects and exposed, 

 for 15 minutes on a bright, ivarm day when in full bloom, thus bringing about the auto- 

 matic tripping of its flowers. 





Number 

 of flowers. 



Number 

 of pods. 



Flowers 

 bearing 



pods. 



Number of seeds. 



Eaceme. 



Total. 



Average 

 per pod. 



No. 1 



26 

 16 

 12 

 17 

 20 

 18 

 12 

 22 

 14 

 14 

 16 

 18 

 17 

 17 

 24 

 12 

 20 



10 

 3 

 3 



8 

 5 

 4 

 1 

 3 

 2 

 1 

 2 

 2 

 6 

 4 

 5 

 4 

 7 



Per cent. 

 38.4 

 18.7 

 25.0 

 47.0 

 25.0 

 22.2 



8.3 

 13.6 

 14.2 



7.1 

 12.5 

 11.1 

 35.2 

 23.5 

 20.8 

 33.3 

 35.0 



13 

 6 

 7 



10 

 14 

 8 

 3 

 6 

 4 

 2 

 4 

 5 

 12 

 10 

 10 

 7 

 12 



1 3 



No. 2 



2 



No 3 



2 3 



No 4 



1 2 



No. 5 



2 8 



No. 6 



2.0 



No. 7 



3.0 



No 8 



2 



No. 9 



2 



No. 10 



2.0 



No. 11 



2.0 



No 12 



2 5 



No. 13 



2.0 



No. 14 



2.5 



No. 15 



2 



No. 16 



1.7 



No. 17 



1.7 







Total 1 



295 



70 





133 







23.7 



1.9 













In 1910 an experiment was conducted at Pullman, Wash., for the 

 purpose of determining what proportion of flowers became self- 

 tripped. Accordingly, nine alfalfa plants, which were producing 

 more pods and seeds than most of the alfalfa plants in the experi- 

 mental plats, were inclosed in netting tents and were closely ob- 

 served for several days. 



The tents in which the plants were inclosed were carefully covered 

 with fine-mesh mosquito bar, so that no openings were left for honey- 

 gathering insects to gain access to the flowers. The tents were made 

 large enough and pains were taken so that no flowers which were 

 being watched were in such a position that they could brush against 

 the sides or top of the tent. 



