162 SIDNEY F. HARMER, 
indigo-carmine is excreted in large quantities by the liver of 
Vertebrates, as well as by the kidney; the bile, hike the urine, 
becoming blue soon after the injection of indigo-carmine,— 
suggesting a new analogy between the so-called “liver-cells ” 
of Polyzoa and the liver of Vertebrates. Without going into 
the question of the excretory value of the processes which take 
place in the Vertebrate liver—a question I am not competent 
to discuss—I may express my conviction that the appearance 
of pigments like indigo-carmine, carminate of ammonia, and 
Bismarck-brown in the granules of the walls of the alimentary 
canal in Polyzoa, taken in conjunction with the normal 
appearance, in the same place, of a natural pigment, and the 
ultimate passage of much of that pigment into the “ brown 
body,” is to be regarded as—in part at least—a process of 
excretion. As has been already pointed out, Ostroumoff! has 
definitely formulated the view that the occurrence of ‘‘ brown 
bodies” is correlated with the absence of nephridia, and indi- 
cations of a similar manner of regarding these bodies are not 
wanting in the writings of other observers. 
It is certainly a significant fact that, while the young poly- 
pide-bud is, in most cases, at first quite colourless, brown pig- 
ment soon appears in the wall of the stomach, &c.; and that 
when the polypide degenerates, the most conspicuous feature 
of the “brown body”? is the pigment whose presence has 
suggested that name for the degenerated polypide. In some 
Ectoprocta the ‘ brown body” leaves the zocecium by way of 
the alimentary canal of the new polypide; in others it is 
simply left behind in the zocecium, just as, in many Tunicates, 
the excretory concretions are stored up in various parts of the 
body without ever finding a way to the exterior. 
It has already been pointed out that in B. avicularia 
Bismarck-brown was excreted into the lumen of the alimentary 
canal, enclosed in spherules which were also noticed in the 
normal condition. This fact tends to show that the spherules 
in question are, in part at least, excretory, although their 
1 A. A. Ostroumoff, “Cont. & Et. Zool. et Morphol. des Bryozoaires du 
Golfe de Sébastopol,” ‘ Arch. Slaves de Biol.,’ t. ii, 1886, p. 339. 
