WATER CULTURES 



22 3 



FIG. loo. Top suitable for 

 the support of plants in water 

 cultures. After Detmer. 



ie gat number of possible vitiating circumstances. The me- 

 chanicil qualities offered the plant are generally quite different in 

 suchjests from the substratum afforded by natural soil, and it is 

 diHctHt to imitate the composition of 

 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 



ii many separate individuals. 



a ca- 



f wood or 

 rig from enc 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 &sPhasolus, Triticum, Avena, Zea, or Convolvulus, 

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

 clotlj^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 placed so that the roots only will depend on the fluid in the 

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

 is kept dry. 



