8. HOOKER: PHYSIOLOGICAL OBSERVATIONS 
half after stimulation movement was detected, whereupon the 
fly-leg was removed. After fifteen minutes the tentacle was well 
bent and the gland had moved through an angle of about fifty 
degrees. Marked elongation took place on the convex side near 
the base in Segment 6, and to a lesser extent in Segment 5. The 
concave side remained nearly of the same length as before. The 
region of bending is coincident with the region of elongation on the 
IG Side views of a tentacle in the process of bending, X 22. 
stimulation; b, c and d, successive stages of inflexion; ¢, the fully bent tentacle. 
a, before 
convex side. As the tentacle continued to bend, the area of 
curvature and elongation was extended upward toward the gland 
including Segments 4, 3, and 2, and to a lesser extent downward > 
so as to include a portion of Segment 7. In the ultimate stage 
the curved region subtended an angle of approximately 215 
degrees. Both sides increased in length, but the increase of the 
convex side was eight times that of the concave. Fic. 1 is a 
series of camera lucida drawings made during the inflexion of this 
tentacle. In } the bending region is seen to be restricted at first 
to the lower end and to extend apically in ¢ and d. The final 
