48 SUMMARY OF CURRENT RESEARCHES RELATING TO 



its anterior end. This region is somewhat conical in form, and the 

 long diameter measures not more than from 3-4 mm. The larger 

 hinder portion of the body varies greatly in proportional dimensions, 

 owing partly to the different size which the uterus has at different 

 periods. In the surfaces of the flattened body it is possible to dis- 

 tinguish two lateral from the broader median arete ; the former are 

 brownish or orange in colour, and the latter is of a greyish yellow 

 coloration, washed here and there by whitish spots, and having at 

 certain points the coiled glands shining through. As is well known, 

 there are two suckers, both of which are placed, not far from one 

 another, along the middle line of the body. In addition to the oral 

 and anal pores there is a third- — the genital — which is placed on the 

 ventral sui-face, and leads into a sinus genitalis, and a fourth, which is 

 found on the dorsal surface, and which forms the termination of a 

 canaliculus connected with the vitelline ducts. 



For all practical purposes, at any rate, the fluke may be regarded 

 as being acoelomate, so that the organs are all placed in the paren- 

 chyma of the body. This consists of connective and of muscular 

 substances. The former is the most richly developed, and consists 

 principally of cells, intercellular substance being but feebly developed. 

 Owing to their close approximation to one another the cells very rarely 

 exhibit a spherical form, and they are more commonly rounded 

 polygonal, or laterally compressed. The muscular substance is formed 

 of contractile, thin, elongated, homogeneous, non-nucleated bands, 

 with dark contours after treatment with reagents. They are rarely 

 single, and are ordinarily collected into bundles. It is difficult to say 

 exactly where they have their insertion or their origin ; it would seem, 

 but the question is not settled, that they pass into the connecting 

 substance, which unites together the contractile elements of the 

 cortical layer. 



When sections are made of specimens previously hardened in 

 Muller's fluid it is easy to see that the body-substance is differentiated 

 into two layers, median and cortical, and the differences between the 

 two are exceedingly well marked. The cortical layer is not thick, as 

 is the median, and this difference is to be ascribed to the absence in it 

 of the supporting substance, and of all the more important organs of 

 the animal. In this cortical layer, then, we can make out (1) the 

 cuticle, (2) the outer or subcuticular cell-layer, (3) the dermo-muscular 

 layer, and (4) the inner layer of cells. After giving a detailed 

 description of these parts the author passes to the consideration of the 

 structure of the suckers. In these we may detect a large number of 

 contractile fibre-cells, which are set in three different strata or systems 

 — equatorial, meridional, and radial. 



In the parenchyma of the central or median layer we find (1) a 

 well-developed digestive and an excretory apparatus, (2) organs for 

 the circulation of the nutriment, and for the functions of respiration, 

 (3) male and female reproductive organs, and (4) a nervous system, 

 divisible into a central and a peripheral portion. The digestive tract 

 extends by its terminal branches throughout the whole of the body- 

 substance, and the blind ends of its branches come quite close to the 



