10 HooKER: PHYSIOLOGICAL OBSERVATIONS 
Fic. 1, a and b, with Fic. 2, d and e, illustrates this. The most — | 
apical part which elongated during the process of bending is the ~ 
last to regain its original position. The basal portion, however, — 
does not stop increasing its length until the entire tentacle is_ 
straight. At the end of the reaction, after 23 hours and 10 © 
minutes, the tentacle measured 3.37 mm. It had therefore grown — 
during the process of bending and unbending 0.43 mm. (See _ 
Fic. 3. Side views of the same tentacle before and after the reaction, to show — 
the increase in length, X 22. a is the same as FIG. 1, a; } is the same as FIG. 2, f : 
Fic. 3). A control tentacle which had not been stimulated meas- ‘ 
ured before and after the experiment 2.57 mm. Another measured | 
2.6mm. They had not grown a measurable amount during the 
interval. 
Fic. 4 is a graphical representation of the growth of the 
tentacle. The elongation of the abaxial side is shown by the 
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Pb 
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2 we 
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RURERwaRs 
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N 
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a Wie Sly ao See ng Sa SN Si mS Wee Bie A 
Fic. 4. A graph representing the reaction shown in Fics. 1 and 2, drawn — 
according to data in TABLE I. See text for explanation. | 
