On the Lateral Eyes of Spiders.' 



bv 



K. Kishinouye, Riéakushi. 



Science ('(»liege, Impérial I'liiversity, Tokyo. 



In order to coiiipaiH- Lininlns and spiders with re^jpect to the 

 development of their eye.-. I re-exnmiiied ray sections and found that 

 I had ()\ci-Iooked in my reeent p;i[)er. a very imi>orhint stage in the 

 develo] »nient of the Jateral eyes of sjnders,* so that my views on this 

 ])()int were in part iiicorreet. Tliis ohlio-es me to write ont hriefly the 

 ncnv ronchision J have arrived at. 



,MI (lie lateral eves of sjnders. giaieraJiy three ]»airs, arise from a, 



common thickening of the epiblast 

 on each side at the posterior ex- 

 terna] corner of the lateral vesicle 

 before it is completely cut off 

 from tlie geiieral epiblast — at 

 about the stage ol tlie reversi()n 

 of the emljrvo. Tlie thickening 

 is sligbrly iiiragiiuitdd and con- 

 sists of cells arranged in many 

 irregular rows (fig. A). 



After the process of the re- 

 version of the embryo has greatly 

 advanced, the invagination disap- 



diirsiil 



^ Fig.B. 



ri'iitriil 



viitrnl 



Lougitiiiliual sections through the 

 " optic area " of the lateral eyes. Fig. B 

 shows the "anterior lateral eye'" and 

 "posterior lateral eye'" only. Zeiss 

 2xJ). 



1. This article was published in t)ie Zoologischer Anzeii,'er Xt). 370 of Nov. 2 1SÎ)]. 



* Oil fill- Di'i-flopiDt'iit Ol' Anuii'iii'i. This Journal. Vol. IV. 



