310 



to the posterior side of the brain ; a median line is slightly indicated 

 by the arrangement of the nucleogenous bodies. The tract composed of 

 large nerve fibres with scattered ganglionic cells on the left side is very 

 much more extensive than on the right. 



Comparison Avith the brain of other Arthropods. — So wholly un- 

 like in its form, the want of antennal nerves, and internal structure, is 

 the supra-oesophageal ganglion, or »brain«, oi Limulus to that of insects 

 and the higher Crustacea, that it is very difficult to find any points of 

 comparison. 



Histologically, judging by my specimens of the brain of the lobster 

 which are stained with carmine, the brain of Limuhis agrees with that 

 of other Arthropods in having similar large ganglion-cells; the smaller 

 ganglion- cells, so abundant in the brains of insects and Crustacea, are 

 wanting in Limulus. There are, in Limulus, no balle n-substanz- 

 masses homologous with those of the other Arthropods nor any »mush- 

 room« bodies. 



Topographically the internal structure of the brain of Limulus is 

 constructed on a wholly different type from that of any other Arthro- 

 podous type known, so much so that it seems useless to attempt to 

 homologize the different regions in the two types of brain. The plan is 

 simple in Limulus; much more complex in Arthropods, especially in 

 the brain of the craw-fish, as worked out by Krieger, as in the Deca- 

 podous brain there arise two pairs of antennal nerves besides the optic 

 pair, and in external form the two types of brain are entirely unlike. 

 The symmetry of the brain of the crayfish, as of the lobster and insects, 

 is marked throughout, each hemisphere exactly repeating in its internal 

 topography, the structure of the opposite side ; that of the Limulus is 

 obscure and imperfect. 



III. Mittheilungen aus Instituten, Oesellscliaften etc. 



1. Bitte um embryologisches Material. 



Zur befriedigenden Durchführung meiner in ihrem ersten Theil 

 bereits publicirten Arbeit über die Anatomie menschlicher Embryonen 

 bedarf ich noch einiger gut conservirter Embryonen von 1 — l^j^ (event. 

 bis 2) cm Körperlänge. Präparate dieser dem zweiten Monat zukom- 

 menden Entwickelungsstufe sind in Sammlungen nicht allzu selten 

 und vielleicht findet sich ein oder der andere von den Herren Collegen 

 bereit, mir mit vorhandenem Material auszuhelfen. Zu Gegendiensten 

 erkläre ich mich gern bereit. 



Leipzig (Königstr. 17), den 31. Mai 1880. W. His. 



