1908J CROCKER AND KNIGHT—CARNATIONS 275 



contains, it does not follow that such is the case with all parts of 

 plants or even with the flowers of all plants. It would be interesting 

 to know the effects and toxic limits of illuminating gas and its con- 

 stituents upon various double as well as single flowers. Similar 

 data for the foliage of various plants such as Coleus, which is supposed 

 to be especially sensitive to illuminating gas, would likewise be of 

 interest. 



5. Summary 



1. The flowers of the carnation are extremely sensitive to traces 

 of illuminating gas in the air. 



2. With the Boston Market and pink Lawson three days' exposure 

 to 1 part in 40,000 kills the young buds and prevents the opening 

 of those already showing the petals. The buds of medium age are 

 considerably more resistant. 



3. In the same varieties 1 part in 80,000 causes the closing of the 

 open flowers upon twelve hours' exposure. 



4. This injury takes place directly on the bud or flower exposed 

 and not indirectly through absorption by the roots. 



5. No chemical test is delicate enough to detect the least trace 

 of illuminating gas that will cause serious injury to carnations. 



6. The "sleep" of the carnation is probably often caused by traces 

 of illuminating gas in the air. 



7. Ethylene is even more fatal to the flowers of the carnation. 



8. Three days' exposure to 1 part in 1,000,000 prevents the open- 

 ing of buds just showing the petals. 



9. Twelve hours' exposure to 1 part in 2,000,000 causes the closing 

 of flowers already open. 



10. There is much evidence that indicates that the toxic limit of 

 illuminating gas upon these flowers is determined by the ethylene it 

 contains. 



The University of Chicago 



LITERATURE CITED 



1. Girardin, — , Einfluss des Leuchtgases auf die Promenaden und Strassen- 

 baume. Jahresber. Agrikultur. 7:199-200. 1864. 



2. Virchow, R., Einfluss des Leuchtgases auf die Baumvegetation. Jahresber. 

 Agrikultur. 13-15:237. 1870-72. 



