4 BULLETIN 700, U. S. DEPARTMENT OF AGRICULTURE. 



growth and certain other activities were recorded from time to time 

 throughout the season. The plants used in each station were a pedi- 

 greed strain of Canadian field pea (Pisum arvense) known as the 

 Kaiser variety, cultivated wheat (Triticum durum) known as Ku- 

 banka No. 1440, and mountain brome grass (Bromus marginatus) 

 native to the Rocky Mountains. The seed was supplied by the United 

 States Department of Agriculture and was of good viability. 



PREPARATION OF PLANTS. 



In 1915 seed of the plants grown in the three type stations as 

 climatic " integrating instruments " was planted directly in poto- 

 meters, without previous germination. In order to insure as prompt 

 and uniform germination as possible, the seed, prior to planting, was 

 soaked for 36 hours in water of approximately 65 F. The object 

 of this was to start the plants at as nearly the zero point of growth 

 and development as possible. 



Direct seeding, however, did not prove entirely satisfactory, chiefly 

 because of the lack of uniformity in size and vigor of the resulting 

 sprouts. In the absence of a known method of selecting seeds which 

 would produce comparable plants, the seed used in obtaining standard 

 plants for investigations in 1916 was first germinated and then such 

 sprouts as appeared to be of the same size and vigor were selected 

 for planting. The sprouts were secured by a method which was a 

 modification of the methods employed by Schreiner and Skinner 1 

 and other workers of the United States Bureau of Soils. The 

 procedure was as follows : The seeds were disinfected for 15 minutes 

 in a 1 to 500 solution of formaldehyde in water. Following this 

 they were washed thoroughly and soaked for 36 hours at about 65 F., 

 and then placed in a germinator consisting of a bed of sand over 

 which two moist blotters were laid. The soaked seeds were placed 

 between the blotters and a constant water level was maintained in the 

 bed of sand, by means of a Marriotte flask, at such a point that the 

 blotters were kept well moistened but not flooded. 



When the radicle was well formed the germinating seed was trans- 

 ferred to a second germinator. This consisted of a circular granite- 

 ware pan, 12 inches in diameter and 4 inches deep, the surface of 

 which was covered with waxed (mosquito bar) netting held slightly 

 above the surface of the pan by a glass rod 5 mm. in diameter, so 

 bent as to form a frame. Into the pan a continuous flow of tap- 

 water, the surface of which touched the netting, but never flooded it, 

 was allowed to run. The radicles were inserted through the mesh, 

 leaving the body of the seed partly dry. When the shoot had de- 



1 Schreiner, O., and Skinner, J. J. Some effects of a harmful organic soil constituent. 

 U. S. Dept. Agr. Bur. Soils Bui. 70, 1910. 



