144 STUDIES IN GENERAL PHYSIOLOGY 
my specimens of Sertulariae. 
ly €«Tn place of normal individuals, 
FIG. : 23 
stolons were formed.”* TI have 
observed these abnormalities, 
however, in Gonothyrea Lovenii, 
which I grew in poorly aérated 
aquaria. 
IX. HETEROMORPHOSIS IN GONO- 
THYRZA LOVENII 
Stems of Gonothyrza Lovenii, 
which were cut off close to the 
root and fixed vertically in the 
sand with the tip downward, 
formed new tips at their upper 
basal ends, so that biapical stems 
resulted (Fig. 23). 
The influence of contact 
stimuli upon the longitudinal 
growth of the roots was very 
marked. Roots that were 
brought in contact with 
the surface of solid bodies 
grew many times faster 
than roots growing in the 
middle of the aquarium 
without any such contact. 
1H. Drresca, “ Heliotropismus bei Hydroidpolypen,” Zoologische Jahrbtcher, 
herausgegeben von SPENGEL, Vol. V, p. 150. 
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