1909} BRIEFER ARTICLES 305 
allow the turning of. the wheels, with no extra turns around the latter. 
The error, of course, is greatest from the thread attached to the plant, since 
its alterations of length are magnified in the record. Not only should this 
thread be kept short, but I think a glass filament could advantageously be 
substituted for all of its length except the loop at the plant and the partial 
turn around the wheel. The results of these errors can also be relatively 
minimized by using plants of the most rapid and vigorous growth, such as 
the flower-stalks of bulbous plants——W. F. Ganone, Smith College, 
Northampton, Mass. 
