Dr. James Macnnrpz on Sarracenia adunca. 49 
and falls to the bottom of the tube, where it is either drowned, or 
attempts in vain to ascend against the points of the hairs, The 
fly seldom takes wing in its fall and escapes; but this sometimes 
happens, especially where the hood has been removed to assist 
observation. In a house much infested by flies, this entrapment 
goes on so rapidly that a tube is filled in a few hours, and it be- 
comes necessary to add water, the natural quantity being insuf- 
ficient to drown the imprisoned insects. The leaves of the 
S. adunca and S, rubra of Walter might well be employed as fly- : 
catchers; indeed I am credibly informed they are in some neigh- 
bourhoods. The leaves of the flava, although they are very capa- 
cious, and often grow to the height of three feet or more, are never 
found to contain so many insects as the leaves of the species 
above mentioned. The spreading fauces and erect appendices 
of the leaves of this species render them (I suppose) less destruc- 
tive. | 
The cause which attracts flies is evidently a sweet viscid sub- 
stance*, resembling honey, secreted by, or exuding from, the in- 
ternal surface of the tube. On splitting a leaf it may readily be 
discovered in front, just below the margin, and in greatest quan- 
tity at the termination of the ala ventralis. From the margin, 
where it commences, it does not extend lower than one-fourth of 
an inch. During the vernal and summer months it is very per- 
ceptible to the eye and touch ; and although it may be s 
not discoverable by either, yet the sensation of swi tn 
dily perceived on applying the tongue to this portion of surface. 
In warm and dry weather it becomes inspissated, resembling a 
whitish membrane. Dow a ab ae a A 
* This substance it seems was noticed by Bartram the younger (see the Preface to his 
Travels). I was entirely ignorant of his conjectures respecting it, until long after 1 had 
proved their correctness. 
VOL. XII. H The 
MISSOURI . 
BOTANICAL . 
GARDEN. - 
