PLANTS WHICH EXHIBIT MOVEMENTS IN THE CAPTURE OF PREY. 143 
is exceedingly like that of the animal stomach, and the process may, as in the case 
of Nepenthes, be fairly regarded as digestion. Whether, in carrying out this 
process, the different forms of glands have also different functions, whether those 
of one kind serve principally to secrete and those of the other to absorb, or 
whether, perhaps, the one variety only discharges viscid mucilage to capture the 
prey, and the other only a liquid containing acid and pepsin, are questions not yet 
determined with certainty, although such a division of labour is in itself highly 
probable. 
The similarity existing between the leaf of Pinguicula and the animal stomach 
in respect ‘of their action on albuminous substances was turned to a practical 
application in dairy-farming long before the discovery of the relationship by men 
of science. The very same changes as are brought about in milk by the addition 
of the rennet from a calf’s stomach can be induced by means of butterwort leaves. 
If fresh milk, warm from the cow, is poured over these leaves, a peculiar tough 
mass of close consistence is formed, the “ Tätmiölk” or “ Sätmiölk” of Laplanders, 
mentioned by Linnzeus a hundred and fifty years ago as constituting a very 
favourite dish in northern Scandinavia. In particular, the fact that by means 
of a trifling quantity of Tätmiölk, produced in the manner described, a large 
amount of fresh sweet milk may be also converted into Tätmiölk is specially 
worthy of emphasis, for we learn from it that the substance generated by 
Pinguicula behaves in this respect too, like other ferments. The immemorial use 
of Pinguicula leaves by shepherds in the Alps as a cure for sores on the udders 
of milch cows is also interesting, inasmuch as the curative effect on the sores is to 
be explained by the antiseptic action of the secretion of the leaves in question; 
and a method of healing, used empirically two centuries ago, thus finds confirmation 
and a scientific explanation at the present day. 
Since the curling up and unrolling of the leaf-margin in butterwort is 
accomplished but slowly, the process above described is not at all conspicuous. 
Moreover, the margin of a young leaf is always incurved, and that of a mature 
leaf is also somewhat turned up before stimulation has taken place; so that, strictly 
speaking, we only have to do with a greater or smaller degree of involution, and its 
nature can only be determined by careful observation. 
In the plants which form the second group in this section of carnivorous 
plants, and of which the best known representatives are the various species of the 
genus Sun-dew (Drosera), the movements, whereby the capture and digestion of 
small animals is effected, occur much more rapidly and obviously. These species 
are usually rooted in the damp dark soil of moors. They have also the same 
habitats as Pinguicule, and often enough sun-dew and butterwort are to be seen 
flourishing close together on a patch of boggy ground no larger than one’s hand. 
On Plate II. they are shown thus associated. Drosera rotundifolia, together 
with Pingwicula vulgaris, is there represented, life size, growing in a bed of 
sphagnum amongst sedges on an upland moor. The thing that strikes one most at 
sight of the round-leaved sun-dew depicted, and in general of all the forty known 
