284 GLANDULAR HAIRS: [Cuar. XV. 
immersion, and there were similar spheres in some glands which had 
not been touched by the infusion. 
Erica tretraliv.—A few long glandular hairs project from the 
margins of the upper surfaces of the leaves. The pedicels are formed 
of several rows of cells, and support rather large globular heads, 
secreting viscid matter, by which minute insects are occasionally 
though rarely, caught. Some leaves were left for 23 hrs. in a weak 
infusion of raw meat and in water, and the hairs were then com- 
pared, but they differed very little or not at all. In both cases the 
contents of the cells seemed rather more granular than they were 
before; but the granules did not exhibit any movement. Other 
leaves were left for 23 hrs. in a solution of one part of carbonate of 
ammonia to 218 of water, and here again the granular matter appeared 
to have increased in amount; but one such mass retained exactly the 
same form as before after an interval of 5 hrs., so that it could hardly 
have consisted of living protoplasm. These glands seem to have very 
little or no power of absorption, certainly much less than those of the 
foregoing plants. 
Mirabilis longiflora.—The stems and both surfaces of the leaves 
bare viscid hairs. Young plants, from 12 to 18 inches in height in 
my greenhouse, caught so many minute Diptera, Coleoptera, and 
larva, that they were quite dusted with them. ‘lhe hairs are short, 
of unequal lengths, formed of a single row of cells, surmounted by an 
enlarged cell which secretes viscid matter. These terminal cells or 
glands contain granules and often globules of granular matter. 
Within a gland which had caught a small insect, one such mass 
was observed to undergo incessant changes of form, with the occa- 
sional appearance of vacuoles. But 1 do not believe that this 
protoplasm had been generated by matter absorbed from the dead 
insect; for, on comparing several glands which had and had not 
caught insects, not a shade of difference could be perceived between 
them, and they all contained fine granular matter. A piece of leaf 
was immersed for 24 hrs. in a solution of one part of carbonate of 
ammonia to 218 of water, but the hairs seemed very little affected by 
it, excepting that perhaps the glands were rendered rather more 
opaque. In the leaf itself, however, the grains of chlorophyll near 
the cut surfaces had run together, or become aggregated. Nor were 
the glands on another leaf, after an immersion ‘for 24 hrs. in an in- 
fusion of raw meat, in the least affected; but the protoplasm luing 
the cells of the pedicels had shrunk greatly from the walls. This 
latter effect may have been due to exosmose, as the infusion was 
strong. We may therefore conclude that the glands of this plant 
either have no power of absorption or that the protoplasm which they 
contain is not acted on by a solution of carbonate of ammonia (and 
this seems scarcely credible) or by an infusion of meat. 
Nicotiana tabacum.—This plant is covered with innumerable hairs 
of unequal lengths, which catch many minute insects. ‘The pedicels 
of the hairs are divided by transverse partitions, and the secreting 
