48 SUMMARY OF CURRENT RESEARCHES RELATING TO 



many of the cells of the suh-cuticular layer arc in reality the central 

 protoplasmic elements of the muscular fibres, the contractile elements 

 of which form the musculature on which the investing membrane rests. 

 The fibres consist of a hyaline membrane covering a finely granular 

 and apparently fluid medulla. 



The connective tissue of Spliyranara is composed of branching cells 

 which form a meshwork ; their processes, which are evidently elastic, 

 are homogeneous, the cells arc oval, spherical, or irregular in shape, and 

 the greater part is occupied by the nucleus, with little or no protoplasm 

 surrounding it. 



The excretory system is provided with two anterior contractile 

 bladders which open by dorsal pores ; applied to their walls are large 

 ganglion-cells which, presumably, control their pulsations ; these are 

 effected by the muscular fibres which line the bladders. Each bladder 

 has connected with it a strong lateral stem which gives off numerous 

 twigs to the caudal lamina ; the walls of the trunks are highly elastic, 

 and are, in parts at any rate, j>rovided with muscular fibres. The walls 

 of the finer excretory capillaries rarely exceed 1 fx in thickness, and seem 

 to be formed by a single coat of a homogeneous refracting substance ; at 

 certain points these capillaries present a funnel-shaped expansion, where 

 the membrane terminates ; beyond the mouth of the funnel there is a 

 network of fine intercellular canaliculi ; the mouth lies in the interior 

 of a connective-tissue cell, and the fine canal which leads to it passes 

 through the cell-substance. The funnel, as well as the capillary into 

 which it empties, always has a distinct wall up to the rim of its broad 

 mouth. Cilia hang over this rim into the funnel. 



In connection with the excretory system of Sphyranura the authors 

 describe some remarkable structures which have not, apparently, been 

 observed in other Trematodes. Cells of a polyhedral shaj>e, sometimes 

 with short processes at the angles, and measuring from 37-50 ll, are 

 found scattered throughout the body. The cytoplasma forms coarse 

 trabecule, which usually radiate from the centre of the cell to the 

 periphery, and contains a system of communicating spaces which are 

 empty in the fixed, but often unobservable in the fresh condition; each 

 cell has at one pole a process, with an axial wavy channel connected with 

 one of the neighbouring excretory capillaries, the wall of which passes 

 insensibly into the membrane of the cell. This connection suggests 

 that the cells in question are truly renal. With them somewhat similar 

 structures in other Trematodes are compared. 



The authors have never seen the nervous system so well during life 

 as in Sphyranura, the fibrillation of the plasma of the ganglion-cells 

 being distinctly seen. The ganglion-cells form two masses which are 

 not grouped round the pharynx, but lie at its sides ; these ganglia 

 are connected by two commissures, the stouter of which is supra- 

 pharyngeal, and the more slender infra-pharyngeal ; on either side are 

 two nerve-stems, which are lateral and ventro-lateral in position, the 

 dorsal stems of Distomum isostominn being, apparently, absent from this 

 form. The system of connecting commissures is described. 



The digestive tract is without an oesophagus ; the intracellular mode 

 of digestion plays only a subordinate part ; the soluble digestive ferment 

 seem to be derived from the cells of the intestinal epithelium. Though 

 this new form is hermaphrodite, the male and female organs are quite 

 independent of each other ; the author's observations on spermatogenesis 



