28
SEARCH FOR ANTHELMINTICS
[Vol. XXV, Part I,
tonic contraction and the spasm, which results on addition of the drug, was main-
tained for 10 and 18 minutes respectively (Graphs C and D). The worm appeared to
die at the end of this period and post mortem relaxation followed since no peristalsis
was recorded once the drugs were put in. The tapeworm, however, reacted
differently to extract arecanut (1 per cent). In this solution, after a primary reac-
tion like the control (Graph B), there was gradual diminution in frequency and ex-
cursion of movements of the worm which completely disappeared in 12-15 minutes.
The effect of various drugs on earthworm is shown in Plate IV. The earth-
worms have much stronger contractions normally than a preparation of tapeworm.
The effects of acetyl saponin and extract filic. in the same concentration as tested
on the tapeworm were, slight stimulation followed by progressive depression till
the movements were totally arrested in 1½ hours by acetyl saponin (Graph A) and
in 30-35 minutes by extract filic (Graph C). Extract arecanut (Graph B) had
a similar action on earthworm as on the tapeworm, i.e. a gradual diminution in the
frequency and excursion of movements right from the beginning of the contact
with the solution and causing a complete arrest in about 2½ hours.
DISCUSSION
Earthworm has been largely employed in the screening of anthelmintics ever
since Sollman [1918] reported that the drugs which are non-toxic to the earthworm
are not likely to be active, while drugs which are lethal to this worm may possess
anthelmintic activity. This principle has been followed and confirmed, among
others, by Jenkins and Manchey [1936]. Olkers and Rathje [1941] also reported that
where ascaris and annelids are affected by the same drug, there does exist some sort
of parallelism between their responses. Other workers have, however, strongly
condemned the use of earthworm in anthelmintic studies as 'irrational'. Lamson
and Ward [1936] could not find any correlation between the responses of earth-
worm and roundworm to the drugs that they tested ; Baldwin and Moyle [1949]
also disapproved of the use of earthworm in the screening of anthelmintics because of
important physiological differences between annelids and nematodes. The authors,
therefore, employed both annelids and cestodes, and nematodes for measuring
vermicidal activity in vitro.
Kymographic studies seem to indicate that there is a good deal of similarity
of response between the earthworm and tapeworm towards extract filic. as well as
acetyl saponin although there are minor differences. In these records it is seen
that both the Anagallis acetyl saponin and extract filic. cause an immediate tonic
contraction of the tapeworm and the worm dies followed by post mortem relaxation.
In the case of earthworm, however, there is a stimulation of movements for a short
period before the depression starts which ultimately passes into complete arrest
and death. The earthworm also takes longer time to die than the tapeworm in
these solutions.
Most authors have rejected the use of earthworm in anthelmintic studies on
the basis of differences in behaviour between this worm and the roundworm.
Present studies also show lack of any relationship between the vermicidal activity
of this saponin against these two classes of worms. However, the authors find a