1903-4.] On Aged Specimens of Sagartia troglodytes, etc. 297 
up liquid from sea-water until, on the pressure reaching a certain 
amount, the thread is shot out. Such discharge would probably 
take place only in sea-water, or in some fluid which differs hut 
slightly in density from sea-water.* The Actinia , on entering the 
coelenteron of its captor and becoming surrounded by the denser 
mucous secretion poured out upon it, would probably he rendered 
innocuous, its nematocysts becoming inoperative. Even if the 
mucous secretion merely served to delay the discharge of the 
nematocysts (as is almost certain, for it would prevent or retard the 
access of sea-water), it is probable that the density of the fluid in 
the coelenteron (after closure of the stomodseum) would, from other 
causes, soon increase to such an amount as to then render the 
discharge of nematocysts impossible. That such a change in the 
contents of the coelenteron does occur soon after closure of the 
stomodseum is evident from the behaviour of the young anemones 
described below. Then, again, the mucous secretion which the 
captor forms over its prey would also act as a shield against any 
nematocysts of the latter which might he discharged. We may 
account in one or other of these ways for the apparently uninjured 
condition of the internal structures of the captor. 
Miss Nelson's specimens of Sagartia troglodytes and also of 
Actinia mesembryanthemum i have been very prolific, though only a 
small proportion of the young produced has survived. As a rule, 
most of them disappear within a week or two after birth, some 
being devoured by the adults of their own or other species, and 
the rest disappear in other ways not ascertained. Both species 
breed in early spring : Actinia commences to bring forth young as 
early as the beginning of February, and Sagartia about a month 
* The fact that the nematocysts of Hydroids are able to pass undischarged 
through a. portion of the alimentary canal and into the dorsal processes of 
rEolis, but may be discharged on being extruded into sea-water, supports this 
view. Again, some fish appear to feed with impunity on anemones and other 
Coelenterates, e.g. Peachia hastata is found in the stomach of the cod (M ‘Intosh, 
The Marine Invertebrates and Fishes of St Andrews , p. 37), swarms of an 
Edwardsia in the stomach of the flounder (p. 38), while Virgularia mirabilis 
is also occasionally seen in the cod’s stomach (p. 39). Anemones are some- 
times used on parts of the Scottish coast as bait for cod, and are found to 
answer this purpose well (see, for example, M ‘Intosh, The Resources of 
the Sea, p. 129). Off the south coast of Iceland one of us has seen the 
stomach of a cod full of specimens of Pennatula. 
