Nuclei Tuheris Laterales and the Ganglion Opticum Basale. 35 



composed of large cells. Cajal further states that there is a great difference 

 in form, position and extent between this ganglion of rodents and the above 

 human centers. While I have not yet studied the basal optic ganglion in 

 rodents I am strongly of the opinion that this ganglion in rodents does not 

 differ essentially either in form, position or extent from the basal optic 

 ganglion in man; I base this conclusion on the constancy of this ganglion 

 from man to the cat, and upon Cajal's description and illustration. There 

 is no difficulty in recognizing that the centers, which Cajal describes in the 

 tuber under the names of anterior, posterior and superior nuclei of the 

 tuber, are portions of the substantia grisea and have nothing to do with 

 the nuclei tuberis laterales of man and macacus; the difference in loca- 

 tion of these three nuclei and the fact that there is every reason to believe 

 that the nuclei laterales are not present in the rodents (appearing first 

 in the lemur) renders confusion impossible. Under the name niicleo 

 subventricular Cajal describes (p. 731) a cell column which is beyond 

 doubt homologous with the nucleus paraventricularis hypothalami, which 

 I have described in man and the higher mammals; Cajal's description and 

 illustration (Fig. 604, T) place this fact beyond the possibility of a doubt. 

 Accordingly Cajal's description of the hypothalamus enables us to recognize 

 positively two characteristic cell groups in rodents one of which is homolo- 

 gous with the basal optic ganglion and the other with the nucleus paraven- 

 tricularis hypothalami of higher animals. Concerning the complex of the 

 nucleus tubero-mammillaris we are left in doubt. 



The presence of the basal optic ganglion and the nucleus paraventricularis 

 is certain not only in rodents but even in the marsupials, as is seen from 

 Ziehen's description of the brain of Pseudochirus peregrinus. In describing 

 Fig. 28 he says (p. 713) : Sehr schim ausgepriigt ist beiderseits das Gang- 

 lion opUciim basale (nucleus supraopticus). Rechts sendet es einen lang- 

 gestreckten AusUiufer in das Pedamentum laterale. Ingesammt erstreckt 

 es sich ilber 1.3 mm. in sagittaler Richtung. Seine Zellen messen 21 fi. 

 Frontalwiirts reicht es noch ein wenig iiber den vorderen Chias-marand 

 hinaus. Einen Zerfall in mehrere Zellgruppen, wie ihn Lenhossck und 

 Kolliker bei dem Menschen beschrieben haben. vermijchte ich nicht sicker 

 nachzuweisen. On p. 714 in describing this same section (Fig. 28) Ziehen 

 says: In der grauen Masse zu beiden Seiten des 3 Ventrikcls kann man — in 

 der Reihenfolge von untcn nach oben — folgende The.ile unterscheiden. 

 Vnmittelbar oberhalb des Chiasmas folgt der kleinzellige Nucleus tuberis 

 (evidently the substantia grisea), auf diesen ein gross-zelUger lateraler 

 Kern, in icelchem der Fornixsiiule eingebettet ist (a portion of my nucleus 

 tubero-mammillaris), und ein eben so grosszelUger medialer Kern, welcher 

 der Yentrikelwand unmittelbar anliegt. This latter nucleus is evidently 

 homologous with the nucleus paraventricularis hypothalami, and I 

 thoroughly agree with Ziehen when he continues as follows: Bei der sehr 

 starken Auspriigung des letzeren war ich sehr erstaunt, eine iihnliche 

 Bildung bei anderen Siiugern nirgends beschrieben zu linden. Ich mil den 

 Kern einstweilen als Nucleus subcommissuralis bezeichnen. Ziehen's 



