NOTES AND MEMORANDA. 
243 
and at the same time the nucleus is separated from the hcemo^ 
globin-b earing body just as it is in the Mammalia y but here, as it 
does not there, enters into the blood stream. 
Any discussion of the mode and significance of the formation 
of haemoglobin in the mammalian blood, ought to take cognizance 
of the fact that haemoglobin is formed in the blood of the worms 
above noted, in Insect larvae, Crustacea, and even Molluscs, and 
further that whilst it usually occurs diffused in the plasma of 
the blood it does occasionally, as in the Chaetopods Glycera and 
Capitella, the Molluscs, Solen legumen and Area, sp., &c., take 
the form of special nucleated corpuscles differing from and 
accompanied by the usual amoeboid colourless corpuscles : also 
it is to be noted that just as fat occurs in other cells than 
specialised fat-cells so do we find the muscular tissue of many 
Vertebrates and of some Molluscs (buccal mass) impregnated with 
haemoglobin. And even in one Annelid (the sea-mouse Aphrodite) 
we have the cells of the nervous tissue so rich in it, that the 
nerve-cord is of a deep crimson colour (see ‘ Proc. Roy. Soc.,’ 
No. 140, 1873). — E. Ray Lankester. 
I. On the Mode in which Hydra swallows its Prey. By M. M. 
Hartog, M.A., B.Sc., F.L.S., of the Owens College, Manchester. 
The current idea is that Hydra swallows by taking its prey in its 
tentacles and turning tentacles and all into its stomach. How- 
ever, the part played by the tentacles ceases as soon as the mouth 
comes in contact with the food. The hydra then slowly stretches 
itself over the food in a way that recalls to some extent the 
manner in which a serpent gets outside ” its prey, or in which 
an automatic stocking might stretch itself on to the foot and leg. 
No care seems to be taken, however, to present the easiest point 
for deglutition, and an Entomostracan may be swallowed side- 
ways, for instance. So far are the tentacles from co-operating 
in the act, that they are usually reflexed away from the food ; 
occasionally, however, they are swung forward for a moment 
around the mass as if to ascertain how much remains to be 
swallowed. 
If the prey be at all bulky, immediately after the whole act is 
completed the body cavity is every where filled and on the stretch, 
but after a short lapse of time the body contracts forcibly along 
the long axis, so that the part containing the food is globular, 
supported on a slender foot and with a slender apical process 
bearing the tentacles around the hypostome. 
II. Additional Note on Hydra. By the Same. Since my last 
note I think I have found the clue to the false idea referred to. A 
Hydra that had swallowed a morsel larger than itself disgorged, as 
frequently observed, on my attempting to take it up for examina- 
tion. On finding it half an hour after, three of its tentacles were 
