from the committee at cost, — perforated ones $4.00 per hundred, 

 plain ones $3.50 per hundred. Corks require reparaffining from 

 time to time if they show fungus growth. The same corks are to 

 be used for later growth phases. 



A good quality of ordinary cotton (batting) is best for fixing 

 the seedlings in the corks; absorbent cotton is not desirable (it 

 absorbs water much more readily than ordinary cotton) . Use 

 just enough cotton to hold the seedling securely in position, so 

 that it will not slip downward. The cotton will become com- 

 pressed, as the stem enlarges. The cotton is to be kept dry. 



Jars should be thoroughly washed, rinsed in distilled water, 

 and dried (or each finally rinsed with the solution to be used 

 therein) before using. Each is filled to a point 1 cm. below the 

 lower surface of the cork. A non-perforated, paraffined cork is 

 inserted (to reduce evaporation and other changes during the 

 interim) and the jar is clearly marked with its solution number 

 (wax pencil). When all the jars of a series are thus filled and 

 marked, the work of placing the seedlings is taken up, the cork 

 bearing the five seedlings now replacing the non-perforated cork 

 that previously stoppered the jar. After each jar is supplied 

 with seedlings its jacket is put in place. The jacket should also 

 bear the number of the solution contained in its jar (marked in 

 pencil) . 



The seedlings should be kept from direct sunlight and from 

 laboratory gases or other disturbing influences throughout the 

 process of changing from germination apparatus to jars, and the 

 series of jars is to be placed in the experiment location as soon 

 as all are ready. It is desirable that the placing of all the seed- 

 lings for any comparable series be completed as rapidly as pos- 

 sible, on the same day; the jars may be supplied with their solu- 

 tions on the preceding day, but are then to be kept stoppered, 

 as described above. 



Any series may be set up either as a simple series or in dupli- 

 cate, triplicate, etc., according to the number of cultures in- 

 cluded, the time at the disposal of the experimenter, etc. In all 

 cases the control culture should be in triplicate; i. e., three cul- 

 tures in solution IR5C2 (1/10-increments, 1.75 atm.) are to be 

 included in every series. 



Renewal of Solutions, and Observations During the Five-Week 

 Period of the Seedling Phase. The solution of each culture is to 

 be renewed every 31/2 days (nine renewals in the five- week 

 period). Details regarding the renewals are given below, also 



16 



