REPORT ON THE HYDROIDA. 
XIX 
name of “ nematophores ” and insisted with justice on the differences presented by them 
as affording characters of primary importance in the systematic distribution of the 
Plumularinse. Since then, however, our knowledge of these zooids has been greatly 
extended, and we now know that the character which the term nematophore was intended 
to express is one to which they can lay no special claim. I shall, therefore, not only 
on this account, but more especially because the term nematophore involves two con- 
ceptions which ought to be kept separate, namely that of the fleshy outgrowth and that 
of the receptacle in which this is contained, adopt here the terminology proposed by 
Hincks, and use the term sarcostyle for the fleshy offset from the coenosarc, and that 
of sarcotheca for the chitinous receptacle by which this is protected. 
The sarcothecse occur in the Plumularinse under two principal forms; (1) in that of 
fixed cups or tubes which are adnate by the greater part of their sides or by a broad 
base to the stem of the Hy droid ; and (2) in that of cups which have no adhesion to 
the stem except at the very narrow point of origin, on which they are movable. Both 
kinds are very constant in their form and position. Under the name of nematophore 
they are specially described in the introductory remarks on the Plumularinse of this 
Report. 1 
The contents of the sarcothecse are very remarkable. Many years ago I drew 
attention to the fact that the bodies contained within the sarcothecse had the faculty of 
emitting pseudopodia-like processes, which often extend to a great distance, running 
out free into the surrounding water or running straight along the stem or winding 
around it, frequently sending off branches which may become fused, one into the other, 
and again become separate, while once more the whole might be seen to have withdrawn 
itself into the interior of the sarcotheca. The phenomena thus presented so exactly 
resemble the emission of pseudopodia by certain Rhizopods that I came to the con- 
clusion that the contents of the sarcothecse consist chiefly of free protoplasm as in the 
body of an Amoeba, though often with true thread-cells immersed in it. 
Subsequent researches have, however, tended to modify this view, and the employ- 
ment of the method of staining has led to the belief that the sarcostyles are of a more 
complex structure than I had originally supposed. By the use of this method Weismann 
believes that he has made it evident that the sarcostyles are composed of cells ; further, 
that they are not a mere ectodermal outgrowth, but that besides having an external 
ectodermal layer they contain a solid filiform axial process from the endoderm, surrounded 
by a closed sac-like extension of the mesosarc. 2 
Since I became acquainted with these views I have had no opportunity of subjecting 
to fresh observation the conclusions to which I had been originally led, but any opinion 
1 Kirchenpaueria is the name of a genus which has heen recently defined by Jickeli from some fragments of a 
Plumularian trophosome, in which certain sarcostyles are developed without being enclosed in sarcothecas. The 
naked sarcostyles are here protruded through simple orifices in the perisarc of the stem (Jickeli, loc. cit., p. 645). 
2 Weismann, Die Entstehung, &c., p. 176, pi. vii. fig. 7. 
