(54) 

 but they are soon lost to view as Ikeaa (9) has founa to be 

 the case when stuayin.; methylene blue preparations. 



Sections tl:rou-_/i Actino tra cl;a "peci es , B. , brin^: out quite 

 plainly certain nervous tracts w'r.ich appear as thickeniiigs of 

 the subepidernial nervous tissue ana v/hicl-t correspond in a lar^^e 

 part to the principal nerves aescribed by Masteriian, 



AiTterior to the ^ai-t^lion a section throu^^h the i^ooa siio ws 

 the {:arallel nerves wr.icn run from the anterior side of the gan- 

 .jlion to the anterior ede;e of tiie hood. The boundary of these 

 nerves as sh.own in "Pig, 44 is a little too definite. The sub- 

 epideriT.al nerve tissue which for/as a thin layer below tiie ecto- . 

 derm cells is iiO t shown in the series of sections to be de- 

 scribed. 



■Pcllowin.^ the sections posteriorly we come to the ganglion 



Vv'hich in this specinten has become invaginatea togetr.er with 



the overlying epiaermis so as to form a pit, A cross section 



t'-.rou^h this pit is s ic vrn in ^ii,, 44 (b) , The cavity o +' the 



the 

 pit is lined by epiderrriis, while peripherially v/all of ti:e pit 



consists of the i:ajri;^lion cells and the nerve fibers of the gan- 

 glion, (T'igs, 3b-44(b) ) The nuclei of the ganj^lia are easily 

 made out but it is oiily after stainin.^ yery deeply with iron 

 haematoxylin that the cytoplasm ceuj be seen. Trie invagination 

 in the region of: the gani_^lion is unusual aria is brDUi_t;t about 



