II. K Hutchinson and N. II. J. Miller 



187 



until they reached the culture solution ; the shoot was then tightly 

 plugged round with non-absorbent cotton wool, in order to keep the 

 seedling in position. 



Fio. 2. 



Direct Assimilation of Ammonium Salts hy Plants. 



Senes I. Wheat grovm in Sand. The seeds were sterilised in 

 0'2.5 per cent, solution at 45° C. and sown on agar plates. Germination 

 was quite normal and after o — 4 days the seedlings were transferred 

 to sterilised test-tubes and allowed to grow for a further period of 

 6—7 days. On May 21st, 1908, they were cairied over to 10 Woulff's 

 bottles containing the following amounts of sand and nutrient salts. 



Sand 1200 grams + 2-4 grams CaSOj + 2-4 grams Ca.j{P04)2 



KCl 0-05 gram \ 



KHoPO^ 0-10 „ 



MgS04 + 7H.,0 0-10 ,, I flissolved in .50 c.c. distillofl water 



NaCl 0-0.5 „ 



Fe.,Cln trace j 



Bottles 1 — 3 and 7 — 9 received in addition G grams of CaCOa. The 

 bottles and the Pasteur-Hansen flasks were sterilised in the autoclave 

 at 12.5° C. for half an hour, and after cooling down a solution of 

 ammonium sulphate = 21 OS mgms. of nitrogen was added to bottles 

 1 — 9, and sodium nitrate = 20'74 mgms. to bottle 10. 



At the time of transferring the young sterile plants bottles 7 — 9 

 were inoculated with a culture of nitrifying organisms, and to all the 

 bottles 100 c.c. distilled water was added from the Pasteur-Hansen 

 flask. From time to time the bottles Avere weighed and the losses 

 made up by adding more water, and aeration was carried out ever}' 

 4 — 5 days. 



