NATURE OF EXCRETORY PROCESSES IN MARINE POLYZOA. 159 
the freshly formed funicular tissue, do not develop with their 
cells impregnated with the pigment in question. It will pro- 
bably be admitted that the pigment is deleterious, and that 
certain tissues capable of taking it up retain it in order to 
allow the newly formed tissues to escape its injurious action. 
It may thus be taken for granted that certain tissues of the 
animals investigated have an excretory function, so far as 
certain pigments which are abnormally introduced into the 
animal are concerned. Can it be further shown that these 
tissues, or any of them, are to be regarded as normal excretory 
tissues ? 
In the first place it may be noticed that the marine Polyzoa 
are not known to possess specific excretory organs. The 
‘ intertentacular organ”’ described by Farre,! Hincks,* Prouho,* 
and others, has not been shown to be of sufficiently general 
occurrence in marine Polyzoa to allow it to be regarded as the 
principal excretory organ. Hincks has, indeed, stated that he 
has ‘‘ repeatedly seen a mass of excrementitious matter pass 
into the organ from below,” and that it is “at last ejected, as 
a pellet, through the terminal orifice.”’* This observation 
seems to show that, in those Polyzoa which possess this organ, 
it may really serve for the excretion of the effete products of 
the metabolism of various tissues, and this, together with the 
discharge of the spermatozoa, is the function ascribed to it by 
Hincks. But in spite of the known occurrence of this organ 
in a few species, and of structures like the semilunate pore of 
Microporella Malusii, stated by Pergens? to open directly 
into the body-cavity, it is obviously necessary to look for other 
excretory arrangements in the vast majority of marine Polyzoa 
in which no special structures of this kind have been detected. 
It may next be pointed out that one or two of the pigments 
used in these observations are, in other animals, specially 
‘Phil. Trans.,’ 1837, pp. 408 and 412. 
‘Brit. Marine Polyzoa,’ vol. i, p. Ixxxix. 
‘Comptes rendus,’ t. cix, 1889, p. 197. 
Loc..cit., p. xc. 
‘Zoolog. Aunzeiger,’ Jahrg. xii, 1889, p. 507. 
ao ~ wo i) _ 
