248 



GROWTH OF PLANTS 



metabolism. The fact that foreign toxic chemicals, when supplied to living 

 plants, are also tied up as less toxic glucosides or glycosides tends to con- 

 firm this explanation. Because there are many biologists who are allergic 

 to teleology we have to be careful just how we word this conception. The 

 fact is established, however, that some toxic products of metabohsm and 

 some foreign toxic chemicals, when supplied to plants, are tied up as parts 

 of less toxic glycosides. How the plants acquired this synthetic power is 

 another question. Did those that lacked this power commit suicide with 

 their oa\ti poisons or by absorbing foreign poisons and those that had the 

 power persist in spite of these poisons, or did the power to tie up self or 

 foreign poisons into less toxic glycosides come about in some other way? 



Other Metabolic Changes Caused by Bud-Forcing Chemicals 



Fig. 96 shows several metabolic changes ^'^ brought about by treating 

 intact dormant potato tubers with one of the very effective bud forcers, 



600 



600 



400 



300 



u 



UJ 



I 

 o 



u. 

 o 



H 

 Z 

 UJ 



o 



^ 200 



100 



CATALASE 



48 72 96 



Hours after beginning of treatment 



FiGUBE 96. Some effects of ethylene chlorhydrin vapor on the metabolism of potato 

 tubers. 



ethylene chlorhydrin. It is evident that respiration increase as measured 

 by carbon dioxide output is one of the earliest changes induced by ethylene 

 chlorhydrin treatment ; it is also the one showing the greatest magnitude of 

 change, over 400 per cent of increase 65 hours after the beginning of treat- 

 ment. After the maximum is reached the rate falls rather rapidly and con- 



