Behavior of Tubicolous Annelids 175 
One further query remains, namely, may not these phenomena 
belong to that class of reactions known as physiological reflexes ? 
Again the facts portrayed must be the sufficient reply, and that in 
the negative, I think. It would seem absolutely impossible to 
correlate such recovery times as ten seconds and three hundred 
seconds, or even many of greater extremes than that, at successive 
reactions under an identical stimulus, and with the briefest 
interval between. 
EFFECTS OF CHANGED CONDITIONS 
Attention has been directed in several places to the fact that 
specimens from various habitats exhibited certain indications of 
the fact in the varied types of behavior. In connection with these 
aspects it was suspected that probably other factors might be 
involved in the matter. Accordingly some attention was directed 
to this point, some few of the results being summarized in the fol- 
lowing sections. 
Tem perature 
It was occasionally noticed that specimens showed a somewhat 
sluggish attitude of behavior at early morning, or when the tem- 
perature was below that of other periods. Accordingly a series 
of experiments was made to determine to what degree this might 
prove of consequence. First, specimens were placed in a vessel 
surrounded by ice, and the effects observed. It was found that 
as the temperature was reduced to about 15° C. the worms began 
to withdraw into the tubes and remained thus retracted during the 
continuance of temperatures of that of lower degrees, thus making 
impracticable any tests. Allowing the temperature to return 
toward the normal, about 20° C. or above, it was found that the 
specimens soon resumed normal relations, and reacted as usual. 
In the tables given there may be found a few of very numerous 
experiments made in endeavoring to gain some light on this 
feature of the problem. | . 
It may be assumed, from analogous and long-established facts, 
that in these organisms there is a range of temperature, between 
what are designated as minimum and maximum, wherein the 
