1 00 Report of the Department of Botany of the 



paradoxical. By measuring the water displaced by a bushel of the 

 stones it was computed that the 5.5 bushels of stones occupied 4.84 

 cubic feet of space. Hence, the introduction of the stones into the 

 fumigation chamber reduced the space occupied by the gas from 

 21.56 cubic feet to 16.72 cubic feet. In the same manner it was 

 determined that a bushel (60 lbs.) of potatoes occupies 1544 cubic 

 inches of space. 23 Accordingly, in Experiments 13, 16, 55 and 86 in 

 which the fumigation chamber contained 16 lbs. of potatoes per cubic 

 foot, or a total quantity of 5.7 bushels, the potatoes occupied 5.09 

 cubic feet or nearly one-fourth of the total space content of the 

 chamber. Were it not for the factor of adsorption this would result 

 in increasing the concentration of the gas. As a matter of fact, the 

 concentration of the gas was greatly decreased. 



In our experiments we have been able to bring about injury or 

 avoid it at will simply by varying the quantity of potatoes per cubic 

 foot of space. When the quantity is small injury invariably results; 

 when it is large there is no injury. This holds under all the conditions 

 of humidity, temperature and germination ordinarily encountered 

 in the treatment of seed potatoes. Hence, we conclude that our 

 disaster in the spring of 1912 was due primarily to the small quantity 

 of potatoes per cubic foot of cellar space. 



That serious injury from the gas treatment has not been 

 reported previously is probably due to the fact that small quantities 

 of potatoes are rarely treated in large chambers owing to the large 

 expense for chemicals. Dr. Morse informs us that in his experi- 

 ments 24 at Houlton, Me., the disinfection chamber contained some- 

 what more than ten pounds per cubic foot. However, at other times 

 considerably smaller quantities were treated in the same room and 

 yet no injury was reported to him. Judging from our own experi- 

 ence it seems as if considerable lenticel spotting, at least, must have 

 occurred in the experiments made by Jones and Morse 25 in 1904 

 and 1905. In a tight box containing 8.2 cubic feet they treated 30 lbs. 



23 The average of three tests in which the results varied from 1539.35 to 1550.33 



cubic inches. The specific gravity of the tubers varied from 1.0711 to 1.07S7, the 

 average being 1.0744. Woods and Bartlett (Me. Sta. Bui. 57 : 151) found the 

 specific gravity of potatoes to vary from 1.0604 to 1.1129. Watson, who made 

 numerous determinations on several different varieties grown in different parts 

 of the United States (Va. Sta. Buls. 55 and 56) gives 1.035 as the lowest and 

 1.103 as the highest specific gravity found. 



24 Reported in Maine Sta. Bui. 149:305. 

 K Vt. Sta. Rpts. 17:397-401 and 18:287-291. 



