84 Records of the Indian Museum. [Vol. XV, 



been possible not only to make exact observations on the parasite, but 

 also to refer to all the literature found necessary. The adult parasites, 

 as found in the mesentery, lie in elongated cysts of a creamy-yellow 

 colour. The cysts measure 2-5 to 3 mm. in length. The younger 

 stages are found scattered in the mesentery, the cyst not having been 

 secreted at this stage. 



II. Technique. 



Living worms are dissected out of the cyst in normal salt solution, 

 under a binocular microscope, and are examined alive on a slide with 

 the highest powers available. They are best preserved for whole mounts 

 in an alcoholic solution of Schaudinn's corrosive acetic solution. The 

 salt solution containing these dissected out worms on the slide is first 

 drained off and a few drops of the fixative added to cover them. After 

 about half an hour the fixative is drained off and the usual method of 

 staining and mounting adopted. We found that Heidenhain's iron 

 haematoxylin gave the best results. Serial sections of the worms were 

 cut with a Minot's rotatory microtome and stained with Heidenhain's 

 iron haematoxylin. 



III. The anatomy and development of the adult worm. 



(1) The Cyst (plate v, fig. 2). — The worm occurs, as we have 

 already remarked, in an elongated cyst which varies from 2-5 to 3 mm. 

 in length. Its width is usually -4 to -5 mm. The cyst is cylindrical 

 and rounded at both ends. It is made up of strong fibrous tissue. 

 On opening out the cyst it is found to consist of a single adult worm, 

 with a few young worms which have been produced pathenogenetically 

 in a manner to be described later on. The worm is attached to the 

 internal wall of one of the rounded ends of the cyst by four suckers, 

 which occur at the anterior end of the worm. The anterior extremity 

 of the cyst, which is the same as that of the animal, can easily be dis- 

 tinguished under a lens, or the binocular microscope, owing to a reddish- 

 orange pigment shining through the cyst at this end. It may be stated 

 here that the cyst is in no way secreted by the parasite, but is formed 

 by the tissues of the host itself undergoing a change. Besides the worm, 

 the cyst contains a large number of fat globules and fat cells, which 

 appear to serve as food for the parent worm. 



(2) The adult worm (plate v, fig. 3). — The adult worm is a leaf- 

 like animal resembling a small liver-fluke. It measures 2-4 mm. long 

 and -38 mm. broad. These measurements refer only to the fully grown 

 animals found in the cyst. It is of a milky-white colour, with two more 

 or less triangular patches of orange-red pigment (P.O.) situated near the 

 anterior end, just posterior to the suckers, one on either side. The 

 worm, on examination under a microscope, is seen to consist of an 

 anterior and a posterior extremity. Anteriorly there is a median 

 rostellum-like structure (K), devoid of any armature. Immediately 

 posterior to it are four typical suckers (plate v, fig. 4), arranged sym- 

 metrically round the base of the rostellum. These are circular, having 

 deep concavities, with thick raised, entire, margins. The usual three 



