WATER CULTURES 



223 



Fig. 100. Top suitable for 

 the support of plants in water 

 cultures. After Detmer. 



the great number of possible vitiating circumstances. The me- 

 chanical qualities offered the plant are generally quite different in 

 such tests from the substratum afforded by natural soil, and it is 

 difficult to imitate the composition of 

 the soil solutions. The seasonal con- 

 ditions are also generally reversed during 

 the periods in which such work is at- 

 tempted in laboratories, and the amount 

 of substances already present in a cutting, 

 or seed, tends to lessen the definiteness 

 of the results in the exclusion of any 

 element from the culture solutions. 

 Lastly it is to be said that only a 

 majority of the experiments will succeed 

 even under the best care and most 



favorable conditions, so that all of the tests described below 

 should be performed with many separate individuals. 



292. Water Cultures. Secure a number of glass jars of a ca- 

 pacity of about 2 liters, and provide for each, tops of wood or 

 earthenware which are made with a slot extending from one side 

 to the center, joining a hole made to receive the plant (Fig. 100). 

 Another hole may be made which will hold a stick or rod for the 

 support of the plants. Germinate a number of seeds of any com- 

 mon plant such as Phaseolus, Triticum, Avena, Zea, or Convolvulus, 

 by placing them in a suitable germinator, or between folds of damp 

 cloth. When the roots have attained a length of a few centimeters 

 remove and clean carefully. To place the plant in proper position 

 for the culture test, it should be set upright in the central open- 

 ing of the top, and held in place at first with asbestos fiber, or cot- 

 ton wool, wedged loosely around it, taking great care that the 

 young stem is not bruised in the process. As it grows it may be 

 held to the wooden support by means of cords. The plant should 

 be jdaced so that fhe toots only will depend on the fluid in the 

 jar, and care should he taken that the packing around the stem 

 is kept dry. 



