437 
Curvature of Roots. 
ture was nearer the extremity than when the radicles are 
allowed to grow freely after branding. This is regularly 
observed, and is due to the fact that while increase in length 
is mechanically prevented, differentiation of tissue goes on, 
so that the tissue capable of lengthening is pushed forward 
more and more, until it extends but a very short distance 
from the apex. 
This series of experiments establishes the fact that the 
changes induced in the act of branding, that would ordinarily 
be followed by traumatropic curvature in the course of from 
one to a few hours, remain effective for periods ranging from 
seven hours to more than eight days, if growth is mechanically 
prevented during those periods. 
23. Reversing the order of procedure by branding after 
removal from the cast is still followed by deflection, as is 
shown by the following : — 
Three specimens of Lupinus albus that had been in plaster- 
casts for twenty -six hours were released and branded. When 
next examined, twenty-three hours later, all three showed 
strong traumatropic curvature, one, as shown in Fig. 18, 
being bent nearly at a right angle. After another twenty- 
four hours this specimen presented the appearance shown in 
Fig. 19, which indicates a considerable, though not par- 
ticularly rapid, growth of the part beyond the curve. 
24. Two specimens of Lupinus albus that had been in 
casts two days and eight hours were released and branded. 
When examined sixteen hours later both were strongly 
curved, one nearly at a right angle. Here, again, it was 
noticeable that, after the release of the radicles from the 
casts, the zone of growth was very short. 
25. In connexion with the preceding experiments, and to 
serve in some measure as a check, it seemed desirable to 
ascertain what would follow artificial suspension of growth by 
other means, such as lowering of temperature. 
Seven specimens of Lupinus albus were branded in the 
usual way and then placed in water at o° C , in which they 
were allowed to remain forty-eight hours. When taken out 
