160 - SIDNEY F. HARMER. 
selected by organs which are known on other grounds to have 
an excretory function. 
Kowalevsky,' starting from the well-known facts with regard 
to the excretion of indigo-carmine and carminate of ammonia 
in Vertebrates,? has shown that both these substances are 
removed from the body, in many Invertebrates, by organs 
which are undoubtedly excretory in nature. Indigo-carmine 
injected into the body is excreted, for instance, by the Mal- 
pighian vessels of Insects, by the tubules of the green gland of 
the Crayfish (but not by the end-sac), by the organs of Bojanus 
in Pecten and in other Lamellibranchs, by the kidney in 
Gasteropods, by the brown tubes of Phacolosoma, &c., all of 
them organs which are admitted to have an excretory function. 
Carminate of ammonia was excreted by the end-sac of the 
green gland of the crayfish, by the nephridia of Nereis, by 
the excretory tubes of Tenia, &c. That the removal of 
indigo-carmine is really a process of excretion is shown, for 
instance, by the experiment recorded with regard to Palu- 
dina. On injecting this animal with a mixture of indigo- 
carmine and carminate of ammonia, the tissues were at first 
violet ; after one or two days the blue colour was entirely 
taken up by the kidney, and the animal became red, and the 
red colour itself disappeared after a further interval. 
Additional proof that the removal of these pigments is a 
process analogous to the normal excretory processes is afforded 
by Kowalevsky’s observations that the crystals of (excreted) 
indigo-carmine appear, in the organ of Bojanus of Pecten, in 
the very vacuoles which actually contain normal excretory 
concretions, and that in Phallusia and in Molgula crystals 
of this substance make their appearance in a similar relation 
to the concretions which are normally present. 
Kowalevsky’s observations further show that these two pig- 
ments may be excreted by different parts of the same excretory 
‘ «Biolog. Centralblatt,’ Bd. ix, p. 33, &. 
2 See L. Hermann’s ‘Handbuch der Physiologie,’ Bd. v, Theil i; ‘ Ab- 
sonderungsvorginge,’ by R. Heidenhain, Leipzig, 1883, p. 345, and the 
references there given. 
