VECTOR OF CANINE PIROPLASMOSIS DUE TO P. GIBSONI               359

a sheet of white paper being laid upon the floor of the cage to show up any engorg-
ed ticks that might have dropped upon it.

It is obvious that the foregoing methods, although serviceable in their own
way, entail an amount of attention which it is not always possible to afford in the
midst of other laboratory duties and, moreover, it was repeatedly observed in the
course of trials carried out at this Institute that some loss of ticks was inevitable
when they were fed by any of the methods described above. An intensive series
of experiments was therefore undertaken with a view to devising a method that
would not only effect a substantial saving in time but would also ensure the reco-
very of every single tick on the completion of its feed upon its host. Both these
conditions were found capable of being satisfied to a very large extent in the method
which is to be described presently and which is now adopted at this Institute as a
routine method for feeding ticks on dogs.

The method, which represents essentially a modification of one recommended
by Nieschulz and Wawo-Roentoe [ 1930 ], has for its object the confinement of the
ticks to a circumscribed area on the body of the host until the completion of their
feed. In the original method, as devised by Nieschulz and Wawo-Roentoe, the
ticks were kept confined under a cloth-cover (" Batistdecke ") fixed on to the skin
of the host by means of collodion. To prevent the cloth-cover from being damag-
ed by the dog, the latter was made to wear a collar made of stiff carton (of. Muller
and Glass [ 1926 ], who, too, recommend the use of similar collars for dogs) and
to ensure further security, the hind legs were kept wrapped in a quantity of padding
(" umwickelt "). Experience at this Institute has shown, however, that collodion
is not quite the type of adhesive that can be depended upon to keep the cloth-cover
intact for the requisite period. In this respect, a much superior adhesive was
found in the substance known as " Chatterton's Compound ", which is procurable,
in the form of sticks, from all leading chemists in India (our own supply of this
material was obtained from Messrs. Smith, Stanistreet and Co., Calcutta). The
material is melted before use and is best applied with a small spatula or a glass rod
flattened at one end. Some tests carried out at this laboratory showed that
Chatterton's Compound was practically insoluble in alcohol, but that it dissolved
slowly in chloroform, ether and xylol, so that any of these solvents may be used
in detaching cloth-covers fixed by means of this adhesive. It was, however,
found more convenient in practice gently to peel off the cover, although this
caused a certain amount of temporary pain to the dog. When used alone,
Chatterton's Compound was found sometimes to have a fatal effect upon such
of the ticks as got stuck in this material along the margin of the cloth cover, so
that it was eventually found to be a good plan to effect the initial fixation by
means of collodion and to apply a layer of Chatterton's Compound only along the

                                                                                                              E