THE COMMON TEASEL AS A CAUNTYOROES PLANT 
43 
dainty Lepidoptera are not free from the habit, as shown by the old 
method used for taking the Purple Emperor Butterfly {Apatura 
iris )—that of placing in its haunts the putrid carcase of an animal. 
Again, it is well known that these insects are extremely fond of 
fermenting liquors. On 17th October 1878, at Portslade, Sussex, 
I watched for some time a lied Admiral Butterfly ( Pyrameis 
atalanta ) fluttering persistently round a wine-merchant’s delivery- 
van laden with spirits, which had been left standing in a road. 
Again, in “ sugaring ” for moths, the attraction provided is not so 
much the sugar as the rum or gin mixed with it. Further, it is 
very well known that butterflies and other insects frequently suck the 
fermenting sap which exudes from injured trees *. Clearly, there¬ 
fore, such insects are liable to be attracted and intoxicated bv the 
fermenting liquor usually found in Teasel cups. On the other hand, 
the Hymenoptera are clean feeders, so that the putrid liquor can have 
no attractions for them : consequently, they are very rarely found dead 
in the cups. 
In view of all the foregoing, it is hard to doubt that some con¬ 
stituent of the liquor in the teasel-cups definitely attracts and 
stupefies these many small creatures, causing them to drown. It is 
equally hard to doubt that, this being accomplished, the plant does 
actually derive benefit from the absorption of the highly-nitrogenous 
liquor which must result from their putrefaction in the cups. 
Th is latter conclusion was, indeed, reached definitely by Sir Francis 
Darwin forty-five years ago, and his conclusion was endorsed explicitly 
by his father, Charles Darwin. Sir Francis, in the course of an 
article f on certain “ protoplasmic filaments ” he had observed pro¬ 
truding from the glandular hairs on the leaves of the Teasel, writes 
{op. cit. 270-2) :—- 
“I believe that the plant does profit by the insects caught in the 
cups. . . . But, whether or not the glands which find themselves 
immersed in the putrid fluid of the teasel-cups take advantage of 
their position to absorb nitrogenous matter, there is no doubt.—That 
the protrusion of filaments is not a habit originally developed for this 
special purpose; for . . . the glands on the seedlings, which do not 
form cups and therefore catch no insects, have well-developed fila¬ 
ments. . . . That the function of the protoplasmic portion of the 
filament was originally to assist in the act of secretion, but that it 
has been subsequently utilized by the plant as a mode of nutrition. 
That the protoplasmic filaments have the power of absorbing nitro¬ 
genous matter and that, in the seedlings, they probably absorb 
ammonia from the rain-water and dew. In the adult plants, they 
absorb the products of the decaying insects for the capture of which 
the plant is adapted.” 
Later observations raise doubt as to the part played by the 
“ protoplasmic filaments,” but Sir Francis’s main conclusion still 
stands, and has been held more or less vaguely by others since he 
* For a summary of observations thereon, see Charles Nicholson in Essex Nat. 
xix. (1920) pp. 12-14, 170-171. 
f See Proc. Roy. Soc. xxvi. (1878) pp. 4-8, ancl Quart. Journ. Microscop. Sci. 
n. s. xvii. pp. 169-174; also, much more fully, in Quart. Journ. Microscop. Sci. 
n. s. xvii. (1877) pp. 245-272. 
