PLANTS WITH TRAPS AND PITFALLS TO ENSNARE ANIMALS. 139 
arctic region and amongst the high mountain flora throughout almost the whole of 
Europe, and is very striking owing to the colour of its foliage being a mixture 
of black, violet, and green. The flower, too, is of a sombre dark-violet hue, and 
the entire plant, by reason of this peculiar colouring, gives a truly funereal im- 
pression. We may remark incidentally that the name Bartsia was chosen by 
Linnzeus for this sad-hued plant as an expression of his own grief at the death 
of the zealous naturalist and physician, Bartsch, who was his intimate friend, and 
who succumbed at a comparatively early age to the climate of Guiana. Damp 
black earth in the neighbourhood of springs constitutes the favourite habitat of 
these plants. Upon digging in summer time down to their roots, one sees that 
a few suckers proceed from them, and fasten upon the sedges and other plants 
growing in the vicinity; but one also discovers subterranean shoots having “ root- 
hairs” developed near the nodes, at which are inserted the paired white scales; and 
these “root-hairs” have the function of absorption-cells. Towards the autumn, oval 
buds, likewise subterranean, are matured, in form not unlike horse-chestnut buds 
(see fig. 25°), and composed of etiolated scales arranged in four rows and over- 
lapping one another like tiles, so that only the back of the upper part of each 
scale is visible, the lower part being covered by the scale next beneath it. 
On the visible part of each scale’s convex under surface three sharply projecting 
ribs are noticeable near the middle, whilst the two margins are rolled back so as 
to form a recess in each case. But, as may be seen in the cross-section of a Bartsia 
bud (see fig. 257), one pair of scales lies over the next higher pair in such a way as 
to convert the recesses into ducts. Owing to this construction the interior of the 
bud is perforated by twice as many ducts as there are covered leaf-scales, and the 
orifices of each pair of ducts occur at the spots where the evolute margins of one 
scale begin to be covered by the middle of the next lower scale. On one wall of 
the ducts, i.e. in the recesses, structures like those which occur in the cavities of 
Lathreea are developed, ü.e. stalked glands, each composed of two cells borne upon 
a basal cell; secondly, pairs of hemispherical domed cells; and, lastly, ordinary flat 
epidermal cells (see fig. 25°). There can be little doubt that the whole apparatus 
acts in the same way as in Lathrea, and is adapted to the capture of Infusoria. 
The subterranean buds of Bartsia, just described, are produced late in the sum- 
mer, and aérial shoots arise from them in the course of the following spring. See- 
ing that the foliage-leaves on these shoots are richly furnished with chlorophyll, 
and manufacture organic compounds in the sunlight from the constituents of the 
air and from the fluids imbibed by absorption-cells from the ground, the question 
arises whether an additional supply of nutriment from the dead bodies of captured 
animals can be necessary or even advantageous. We shall, however, taking into 
account the cireumstances of Bartsia alpina when growing wild, answer this 
question with an unconditional affirmative. The plant belongs, as has been said, 
to an arctic and high alpine flora, and grows in regions where the activity of 
plants above ground is limited to the short period of two months. After the lapse 
of this brief vegetative season, the aérial parts of arctic and alpine plants either 
