i 9 i6] RIGG—SOIL TOXINS 297 



Using a modification of Harrison and Barlow's method, they 

 got alfalfa seedlings which grew in sterile cultures for 4 months. 



Brown (4) found that barley seeds take up water from a 

 fairly strong solution of sulphuric acid and remain uninjured. 

 Schroeder (22) found silver nitrate to be a good means of steriliz- 

 ing wheat. He found that hand-picked wheat endured soaking 

 in a 5 per cent solution of this substance for 24 hours without 

 injury, and for 72 hours with but slight injury. Threshed wheat, 

 however, because of the rupture of semipermeable membranes by 

 the machinery, would not stand such prolonged treatment. Archi- 

 chowsky (1) got a large percentage of sterile cultures of seed 

 plants by the use of formaldehyde and other antiseptic agents on 

 peas, pumpkins, and other seeds. 



Solutions and preparations 



Both of the species of Nymphaca used produce branched 

 rhizomes 3-15 cm. thick and sometimes reaching as great a length 

 as 3 m., although they are more commonly 1 m. or less. The 

 older portions of these rhizomes decay. Sherff (23) found these 

 rhizomes decaying to within a short distance of the growing apex. 

 The writer has found the decay only in older portions of the rhizome. 

 Sound pieces of the rhizome were collected and the following 

 solutions were made up quantitatively, each solution having a 

 volume of 1600 cc. and containing the solutes obtained by the 

 methods described from 1000 gm. of fresh rhizome. An average 

 of 3 tests on the water contents of the fresh rhizome gives 88 per 

 cent of water. The tests were made by cutting 500 gm. of the 

 fresh material into small pieces and drying it at 105 C. 



Solution 1 A. — This was the liquid resulting from the decay 

 of 1000 gm. of fresh Nympkaea rhizome in redistilled water, freed 

 from solid matter by filtering through cheesecloth, and diluted 

 to 1600 cc. with redistilled water. Molds continued to grow 

 on the surface of this solution. It was amber colored. 



Solution iB. — This was the solution remaining after a duplicate 

 of iA had been extracted by shaking with an equal volume of 

 ether in a separatory funnel. The ether that dissolved in the 

 water solution was removed by heating to 40 C. and subjecting to 



