438 Potter . — Method of demonstrating the Heat of Respiration, 
Pierce (‘ Botanical Gazette,’ 1908, 1912) has employed the Dewar flask 
with drainage tubule in his investigations on measuring the number of calories 
liberated by germinating peas, and has also emphasized the necessity of 
measuring the heat equivalent. In his experiments he has also avoided the 
error due to the heat of putrefaction by sterilizing the seeds. 
Armstrong College, 
N EWC ASTLE-U PON-T YN E, 
March , 1917. 
