Anatomy. — " ContriZ/utions to the hioivleJc/e of the bruin of bony 

 fishes." By Pi-of. Kyozo Kudo, Mukden (Manchuria). (Com- 

 municated bv Dr. C. U. Akiëns Kappkrs). 



.Communicated at the meeting of January 27, 1923). 



1. I'he Tr. olfactorio-opticu.-i. 



Nils Holmgren found in Osmerus e|»erlanus with tlie CAJ.^i.-niethod, 

 but ai^o witli meihylene-biue colounng, a bundle wliich, long before 

 the middle of the telencephalon, separates from the tr. olfaclorius 

 lateralis, then, following the tiulcu.s externu.-?, extends as far as the 

 opticus, into which it enters, and can be traced (in the opticus) 

 for some distance towards the eye. He called the bundle tr. olfactorius 

 lat. optici (op. cit., p. 188). Witii Callionymus lyra he found a 

 'similar bundle, but lying in the medial olfactory tract 'I.e., p. 188, 

 Aiunerkung). 



This discovery should be considered most remarkable. Being able 

 to test and confirm the latter case (the fibres in the tr. olfactorius 

 med.) with various Teleosls also by WEiGERT-preparations, I will 

 describe it here more fully. 



With the WF.iGRRT-colouring these fibres, connecting the tr. olfacto- 

 rius with the tr. opticus, seem fairly coarse; they are nearly always 

 scattered and mixed only with the tr. olfactorius medialis, never with 

 tr. olfactorius lateralis, in the bony fishes, which I examined they 

 run always the same way. As these relations are the most distinct 

 in Ammodytes tobiauus, I lake this fish as example. 



With this fish the tr. olfactorius med. consists of two sorts of 

 medullary fibres, a thin one and a much coarser one. The fibres 

 divide into three parts 



The pars dorsalis is that part of the tr. olfactorius med. that 

 on a quite frontal level turns towards dorsal. It consists for the greater 

 part of thin fibres that radiate in dorso-lateral direction and disappear 

 rather soon, already on the level of commissura anterior. A few 

 coarse fibres, however, also belonging to this portion, run further 

 caudad, always following laterally the tr. olfacto-hypothalamicus 

 med., but strongly contrasting with these by their coarseness. They 

 cannot be traced accurately from the place where they medially 



5 



Proceedings Royal Acad. Amsterdam. Vol. XXVI. 



