STUDIES ON THE ECTOPA.RASITIC TREMATODES OF JAPAN. 49 



one another by intervening spaces -which in sections appear perfectly 

 colourless j but in many cases the protoplasm of adjacent cells is con- 

 tinuous, and no boundary can be recognised between them (PI. XIV, 

 fig. 2). . In Hexacotijle grossa (PI. XIV, fig. 6) and Tristomum siniiatum 

 (Pis. XXI and . XXII), the endoparehchyma is a true syncytium 

 traversed, however, by scattered connective tissue fibres. The nuclei 

 are very irregularly, distributed ; and in both species they are much 

 smaller than in others. In Hexacotijle grossa I have observed, scattered 

 here and there apparently without order in the general syncytium, 

 cells of irregular forms, with a homogeneous protoplasm which was 

 well stfiined by haematoxylin, but differently from the general 

 syncytium (PI. XIV, fig. 6, x), which was stained deep blue, while 

 the cells above mentioned were stained purplish red, just the colour 

 of acetic haematoxylin. I have occasionally observed similarly 

 stained cells in Onchocotyle spinacis. These cells have, so far as 

 I have observed, no relation with the glands hitherto described 

 or to be described hereafter ; and the only suggestion that I 

 can give as to their nature is that they are perhaps worn-out cells 

 undergoing disintegration, and that their colour is due to ihe presence 

 of some acids generated by decomposition. In Tristomum sinuatum, I 

 have often observed in the peripheral portion of the endoparenchyma 

 cells (already referred to in describing the investing membrane) of 

 a rounded outline and with a granular protoplasm. I do not know 

 what else they are than remnant cells of the original mesenchyma. 



Around the terminal portions of the genital ducts, the mesenchyma 

 is specially modified in various ways. These will be treated of in con- 

 nection with the genital organs. 



If, now, we make a general survey of the various forms of endo- 

 parenchyma found in the monogenetic Trematodes, we see that 

 even in the same species it is very different in different parts of the 



