BRAIN OF THE 'WHITE ANT' 573 



projections from the lateral surfaces of the brain, and a slender 

 optic nerve passes from each greatly reduced compound eye to 

 the optic lobe. In a frontal section of the worker brain (fig. 25) 

 the small inner, middle, and outer fiber masses may be distin- 

 guished in the optic lobes, and also the fibers of the distal part 

 of the optic nerve. By carefully following the optic nerve in 

 subsequent sections it may be traced to the vestigeal compound 

 eye. 



The condition of the compound eyes evidently varies con- 

 siderably in different termites. Holmgren ('09), describing the 

 optic lobes in the worker of Eutermes, ^\Tites as follows: 



Die Reduktion der Facettaugen hat eine entsprechende Rediiktion 

 der Sehganslien mitgefdhrt, Die Sehnerven sind vielleicht vorhanden 

 aber enthalteri nur wenige Nervenfiidchen iind von den bei den Ge- 

 schlechtstieren, bcsonders den jungen, so wohlentwickelten Seliganglien 

 kann man gar nichts cntdccken. Die Seiten des Protocerebralganglions 

 sind somit kreisformig abgcrnndct. 



The optic lubes of the soldier, like those of tlie worker, a])])ear 

 as small rounded projections on tlie lateral surfaces of the jwoto- 

 cerebrum (fig. 12, o.L), with optic nerves extending to the still 

 smaller vestigeal compound eyes, c.e. On account of the very 

 hard chitin of the soldier's head no attempt was made to sec- 

 tion the entire head. The brain was dissected out, under a dis- 

 secting microscope, stained, embedded, and then cut in frontal 

 sections. A section through the optic lobes (fig. 22, o.L) shows 

 that the inner, middle, and outer fiber masses, although small, 

 are clearly distinguishable, and that fibers enter the outer fiber 

 mass from the optic nerve. 



Holmgren ('09) states of the soldiers of Eutermes: 



Die Soldaten sind ja blind und deshalb sind die Sehganglien voU- 

 stiindig vcrschwunden. Man kann von denselben kein Spur ent- 

 decken, obwohl ein sehr dinner n. opticus meistens vorhanden ist. 

 Dieser fungiert aber als Hautnerv. Zufolge des Fehlens der Sehganglien 

 sind die Seiten des Protocerebrums beinahe ki-eisrund. 



The optic lobes of the true adult have not been studied in 

 sections. 



