178 s. GOTO. 



^ vil. The Nervous System. 



With the excellent investi ligation of Lang" on the nervous 

 system of the Trematodes before nie, I directed my special attention 

 to this svstem, and can confirm his statement in its general aspect, 

 though it seems to me to require modification when the writer ex- 

 tends it to the Trematodes in general. Let us begin with the brain. 



As to its position, Lang says, "Ich glaube überhaupt, dass bei 

 allen Trematoden das Gehirn diese Lage hat, dass es nämlich bogen- 

 föi-mig über den vorderen Theil des Pharynx verläuft und ich zweifle, 

 ob sich die abweichenden Angaben bei erneuter, genauer Untersuchung 

 bestätigen würden." Leuckart-' is inclined to explain those cases where 

 the brain has been observed behind the pharynx "durch eine Lagen- 

 veranderuns" " of the latter, " die um so leichter eintreten kann, als 

 das Nervenband nirgends ringförmig geschlossen ist, obwohl das für 

 einzelnen Arten behauptet wurde." T find, however, after careful and 

 repeated observations, with these statements full in view, that in Diplo- 

 zoon and also in Axhie, Microcotijle, and Oclohothnum^ the brain is a 

 band-shaped nervous body arching over the oesophagus on the dorsal 

 aide and heJiind the pharynx. In a fresh specimen, it is seen to be 

 composed of very thin fibres ; but sections shew that in addition to 

 these fibres the brain contains a finely granular substance doubtless 

 identical with the " Punktsubstanz " of the Turbellarians (Fig. 17). 

 The fibres in the brain are seen to run mainly in two groups, one on 



by Looss, for the funnels, and overlooked these latter. I also belive that they go too 

 far when they endeavor to attribute excretory nature to the large cells observed by Looss and 

 others in the pharynx of many Tiematodes. 



1) Lang — Untersuch, z. vergleich. Anatomie u. Histologie d. Nervensystems d. Plathel- 

 minthen. Mitth. a. d. zool. Station z. Neapel. Bd. II. 1881. p. 28. 



2) Leuckart— I.e. p. 22. 



