Behavior of Tubicolous Annelids 167 
more or less vigorously and somewhat indiscriminately, and again 
with substantially the same results as just cited. [ then tried 
a somewhat different test, namely, forming a bruslt out of a 
tuft of very delicate red alga; this was used as a tactile instru- 
ment. While it was possible by extreme delicacy of touch to 
gently jostle the gills of specimens, there was an appreciable dif- 
ference as compared with that associated with the foregoing. 
Tt was also found that by using a gentle current of sea water ejected 
from a pipette against the gills the specimens would frequently 
bear considerable disturbance without reactions. An attempt was 
made by this means to train specimens to allow similar jostling 
by means of a delicate glass rod, ejecting water from a pipette in 
one hand and with the other touch the gills with rod. But it was 
of small avail. In almost every instanec the slightest touch of 
the foreign body induced the usual sharp response of retraction. 
It would seem, therefore, that we have in this type of behavior 
an example of tactile discrimination of a qualitative nature, enab- 
ling them to distinguish as to the nature of the stimulus. It should 
be noted, however, that in this matter as in that of the shadow 
stimulus, there was marked individual variation of behavior, and 
furthermore that these differences varied more or less from day 
to day. 
It was pointed out in the former paper that following certain 
experiments a degree of shyness or caution was induced. The 
same thing was quite as marked in the tactile experiments here 
under review. And in the present case the tests were made with 
smooth and delicate rods which involved not the slightest injury, 
such as was involved by the clipping of gills with scissors; still 
there was almost invariably involved the development of a degree 
of caution which was quite marked. Following a given test the 
specimen would protrude only the tips of the gills, followed by a 
pause; then a further protrusion, then another pause, and often a 
slight retraction; finally a further protrusion and the expansion of 
the crown of gills as usual. 
