CHROMATOLOGY OF BLOOD OF SOME INVERTEBRATES. 473 
marmoratus, Maja verrucosa, Pilumnus villosus, 
Squilla mantis, and in all has seen the blood become blue 
by shaking with air and oxygen, and the blue colour disappear 
more or less with C0 2 . He thinks it probable that a part of 
the hsemocyanin or of its uncoloured reduction product becomes 
decomposed or insoluble in the blood after some hours’ quiet 
standing. In Limnseus stagnalis he found that the blood 
after becoming blue on exposure to air was hardly changed in 
colour on shaking with C0 2 ; now, it seems to me that a 
current of C0 2 ought to be conducted into the blood before 
one can arrive at a negative conclusion. Krukenberg, however, 
thinks that in the blood of Helix pomatia and aspersa, and 
of Limnseus stagnalis a body exists which is at least very 
nearly related to hsemocyanin. Perhaps he might have gone 
further, and concluded that hsemocyanin is present, as Fredericq 
has shown for the first species to be the case. Krukenberg 
also found great differences in the blood of individual Gastero- 
pod Mollusks, which led him to assume that perhaps the 
oxygen in such cases is in a firmer combination with the 
hsemocyanin than is the case in Crabs and Cephalopods. He 
also made the interesting observation that the blood of Crabs 
and Cephalopods on treatment with carbonic oxide became 
colourless, but regained its blue colour on shaking with air. 
This behaviour is different from that of haemoglobin when 
similarly treated. It was further found that blood which 
had become blue by reception of oxygen if allowed to stand 
in a test-tube exposed to the air did not lose its blue colour 
from above downwards, but from below upwards, whence he 
concludes that the blueing is not due to suspended particles, 
but to the presence of a chromogen which becomes blue 
by reception of oxygen. With H 2 S the blue Crabs’ and 
Eledone’s blood became a feeble yellow, and lost the property 
of again becoming blue with oxygen. He could find no 
haemocyanin in the blood of several Mollusks (e. g. Tethys 
fimbria, Doris tuberculata, Aplysia depilans, Pleuro- 
branchus, &C. 1 ). 
1 Krukenberg further shows that (besides Planorbis in which the blood is 
