STUDIES ON THE ECTOPAEASITIC TREMATODES OF JAPAN. 147 



formed of n, connective tissue -whose fibres are arranged mainly at right 

 angles to the outer and inner limiting membranes. We have, there- 

 fore, an. almost complete series, of stages from the ordinary fibrous, 

 reticulated connective tissue, to the compact substance consisting of re- 

 fractive, prismatic fibres, which constitutes the wall of the suckers of 

 Axine, Microcotylc, Octocotyle,. Dlclidophora, liexacotijle, andLOncliocotyle, 

 (the anterior sucker excepted in the last genus) and the hemispherical 

 or cylindrical organ around the genital atrium of some species of them. 

 The prismatic fibres seem to be formed by. a transformation of the 

 granular substance usually present in the meshes of the connective 

 tissue, while the connective tissue fibres themselves appear to remain 

 mostly unchanged and are seen well stained in sections. 



As. I have said above, we have no positive proof that the prismatic 

 fibres in question are non-contractile; but! their genesis as above ex- 

 plained seems to me to exclude the view which regards them as of 

 muscular nature. 



If now the fibres that constitute the wall of the suckers of the 

 genera above mentioned are non-contractile, the question arises how is 

 the suctorial action to be explained. Lorenz'^ indeed has denied such 

 an action to the posterior organs of attachment of Microcotyle and Axine, 

 and has called them simply " Haftorgane"; but that they are true suckers 

 is beyond doubt; for I have observed living specimens of Microcotyle 

 attach themselves to a glass slide by means of the posterior suckers. I 

 have also observed them execute a leech-like locomotion by alternately 

 attaching and detaching the anterior and posterior ends of the body; 

 and I can not see how the worm can attach itself to a glass slide un- 

 less the action of these posterior organs of attachment be suctorial. 

 The anterior suckers must also be able to exercise suction; for in 

 Microcotyle there is no other organ at the anterior end of the body, by 



1). Lorenz— Z. c, p. G. 



