434 Spalding . — On the Traumatropic 
and the number plainly deflected in each lot, there could 
be no doubt that those wounded deeply enough to cut the 
growing-point itself showed more pronounced traumatropic 
curvature, and in a greater number of cases, than those in 
which the root-cap alone was wounded. 
Suspension of Growth and its Relation to Traumatropic 
Curvature. 
Growth, as already shown, is a necessary condition of 
traumatropic curvature, and it is of interest to ascertain 
whether, if growth is suspended by artificial means, curvature 
takes place when it is again resumed. In view of the fact' 
that differentiation of tissues continues in spite of the sus- 
pension of normal growth, it might well be questioned 
whether the conditions induced by the infliction of a wound 
still induce curvature, notwithstanding the histological changes 
that have meantime taken place. Accordingly, repeated ex- 
periments were made by first branding radicles and then 
confining them in plaster-casts for longer or shorter periods, 
after which they were released and allowed to resume their 
growth. The results were so striking that it seems worth 
while to give a considerable number of them in detail. The 
experiments were begun on January 8, 1894. Three species 
were employed, viz. Lupinus albus , Vicia Faba , and Zea 
Mais. Vigorous specimens were selected, when the radicle 
was making a strong and normal growth, usually when it was 
about 2 cm. long, though some longer and others shorter than 
this were used. 
16. Three radicles of Lupinus albus were branded and 
placed in plaster-casts, after which they were left in moist 
sawdust twenty-two hours, care being taken, as in other 
cases, to have them stand vertically and thus avoid com- 
plications due to geotropism. At the end of the twenty-two 
hours they were released from the casts and allowed to grow 
in water. In one hour and ten minutes curvature could be 
detected, and at the end of twenty-four hours, when next 
examined, all three had become strongly curved. Fig. 8 shows 
