20 BULLETIN 75, U. S. DEPARTMENT OF AGRICULTURE. 
- flowers that were tripped and the pods that developed from tripped 
and untripped flowers are shown in Table XI. 
TaBLe XI.—Pods and seeds from automatically tripped alfalfa flowers at Chinook, 




Mont., 1909. 
Number of flowers. Number of pods. 
SNE S| | Blowers 
Raceme Flowers f 
EE No. d tripped. From_ |From un-| Dearie 
Total. | Tripped. Total. | tripped | tripped | P°°- 
flowers. | flowers. 
Per cent. Per cent. 
INGGO ee one 34 12 9 75.00 7 7 0 58.33 
INGA Sn Ree Bees 35 11 3 27.27 3 3 0 97.27 
NO So eet cs Lee ae 36 7 2 28.57 0 0 0 
Nos Siakte. ie 37 il 7 63. 63 5 5 0 45. 45 
TS OCA OAL DENN 38 10 9 90. 00 5 5 0 50.00 
NGS escent 39 6 3 50. 00 1 1 0 16. 66 
Motalesaeee lee aware 57 CGY aaa 03 30 21 21 0 les. 
PAV OTAS OLS sian| calsiewrse eels ce comets Lhe fayoete ails lyk EY Paschal paid Pa SU Fl te eee S| [KU 36. 84 
iNT em eee | 30 14 5 35.71 3 | 3 | 0 21.42 
Noo Sateen 31 6 2 33.33 0 0 0 
IND Se is Soe 32 20 14 70.00 8 8 0 40. 00 
TN (ay Oe SCO 33 11 2 18.18 0 0 0 
IN ORS Ee i eae S 34 13 13 100. 00 5 5 0 38. 46 
Dotatven cater Veni 64 Rey Seed 16 | 16 0 | Pea: 
PAV CLAP Cae | Scie ce seme lcci ceite | a eiesie es | 56125) ose [Ee PcRS See eee | 25.00 
Hlowersiiripped:.on plants 3.andi6.:441.32 2207028 ee per cent.. 57.02 
Flowers producing seed on plants 3 and 8._._....-----..------ dorstes 30. 57 
Tripped flowers producing seed on plants 3 and 8_.__-------.. Goon 53. 62 
Untripped flowers producing seeds on plants 3 and 8.---.------ dos 0 
At Arlington farm, Virginia, in 1909, an entire alfalfa plant was 
inclosed in a screen of tarlatan about the time the first flowers came 
into bloom. Ten days or two weeks later the plant was observed 
to be in full bloom. When the screen was removed it was noticed 
that the flowers seemed larger than those on plants that had not been 
screened. Seventeen racemes were tagged to show the number of 
flowers on each, all unopened flowers being removed. The screen 
had been removed only two or three minutes when a snapping or 
clicking sound was heard. On close observation it was found that 
some of the flowers had become tripped. The sound of the column 
striking the standard was quite distinct, but even with very close 
watching no single flower was actually seen in the act of tripping. 
No insects visited the flowers of this plant, and the only way in which 
the flowers could be tripped would be automatic. The day was clear, 
very warm, and with no breeze stirring. The screen was removed 
about 11 o’clock in the morning and for not more than 15 minutes. 
No actual count of the flowers tripped in the manner just described 
wasmade. At first the flowers did not trip very fast, but as the plant 
remained longer in the sunshine the trippings became more frequent. 
At times three or four would be heard almost simultaneously. The 

