PLATE 33 



A. — Grapefruit roots, 12 days old, grown in distilled water. 



B. — Grapefruit roots, 12 days old, grown in distilled water plus 100 parts per million 

 water-soluble peat. 



C. — Lemon seedlings, 21 days old, grown in carbon-treated distilled water. 



D. — Lemon seedlings, 21 days old, grown in carbon-treated distilled water plus 

 calcium carbonate. 



E. — Grapefruit seedlings, 20 days old, grown in carbon-treated water. 



F. — Grapefruit seedlings, 20 days old, grown in carbon-treated water plus calcium 

 carbonate. 



