Behavior of Tubscolous Annelids ISI 
have since come to light which seem to have still more convincing 
significance, and a few further suggestions may be pertinent. 
Whatever of doubt may be involved in the observations and inter- 
pretations of the behavior of living organisms, whether in the 
aquarium or the native habitat, the aspects of behavior portrayed 
in the present case by the tubes themselves are beyond all dispute, 
at least as to matters of fact. In these structures there has been 
left a graphic and authentic record of behavior no less certain and 
convincing than that of fossils. Hydroides have literally litho- 
graphed a picture of behavior in minutest detail, a valid inter- 
pretation of which calls for no abstruse speculation nor the pro- 
jection of novel or pretentious theories. These tubes are explicit 
expressions of the physiological and ecological activities of the 
creatures which build and occupy them, as certainly as are the 
structure and architecture of human habitations expressions of 
certain aspects of human life. Hence in these tubicolous struc- 
tures one may trace the varying aspects of growth and behavior 
from week to week throughout the entire life history with a sense 
of assurance not easily disconcerted by the scare-crow of anthro- 
pomorphism. 
There is no occasion for dogmatism on this point. One may 
not always be certain that a given interpretation may be beyond 
dispute, but as facts multiply involving data of habitat, distribu- 
tion, experimentation, etc., doubts become less doubtful, and may 
give place to substantial certainty. _ Such is thecase in the present 
instance. Facts have accumulated covering almost every phase of 
life history, from the emergence of the trochophoreto the period of 
its attachment, and on through the whole of its varied life, both 
under artificial and natural conditions. 
In the earlier paper attention was directed to Zeleny’s observa- 
tions as to the behavior of young worms at the time of attachment 
in relation to light and gravity.?. I have had recent opportunity 
to study the still earlier behavior of the trochophore itself, and also 
the aspects of the youngest tubes of the attached larve in natural 
conditions, which serve to still further confirm the former con- 
7 Biol. Bul., vol. viii, p. 309. 
