1094 domestieus), viz., a transverse and a sagittal WEIGERT-PAL~paracarm<strong>in</strong>e series, a horizontal WEIGERT-PAL~alum~carm<strong>in</strong>e series, and a transverse series sta<strong>in</strong>ed for cells by HUBER's toluid<strong>in</strong> blue method. Hav<strong>in</strong>g found the <strong>nucleus</strong> sought for, it was also studied <strong>in</strong> a transverse WEIGERT-PAL series, countersta<strong>in</strong>ed with various sorts <strong>of</strong> carm<strong>in</strong>e, <strong>of</strong> the dove (Columba domestica) and <strong>in</strong> a transverse HUBER series <strong>of</strong> the same anima!. This bird, due to the stronger development <strong>of</strong> the olfactory system, proved better suited for the study <strong>of</strong> the connections. An <strong>in</strong>spection, <strong>in</strong> the sparrow, <strong>of</strong> the foremost part <strong>of</strong> the thalamus, the region where the <strong>nucleus</strong> <strong>of</strong> <strong>BELLONCI</strong> is found <strong>in</strong> reptiles and mammais, immediately revealed the presence <strong>of</strong> a clearly circumscribed <strong>nucleus</strong>, whieh by its general appearance made the impression to be the sought for structure. As <strong>in</strong> the cases, so far known, it was a small ellipsoidal body, whose neuropil sta<strong>in</strong>ed strongly with paracarm<strong>in</strong>e. In the dove about the same relations were found. As was to be expected, this clearly circum~ scribed and rather conspicuous <strong>nucleus</strong> had been described before. It appeared to be the <strong>nucleus</strong> lateralis anterior <strong>of</strong> EDINGER and WALLENBERG (1899), a cell group about whieh, despite its dist<strong>in</strong>ctness, a great con fusion has arisen, whieh I shall try to disentangle at the end <strong>of</strong> the paper. I shall start to put forward my f<strong>in</strong>d<strong>in</strong>gs <strong>in</strong> the sparrow, and already now shall speak <strong>of</strong> a <strong>nucleus</strong> <strong>of</strong> <strong>BELLONCI</strong>, leav<strong>in</strong>g the argumentation for later. In the sparrow the <strong>nucleus</strong> <strong>of</strong> <strong>BELLONCI</strong> is an ellipsoidal body <strong>of</strong> dense neuropil with numerous, mostly small cells <strong>in</strong> it, ly<strong>in</strong>g immediately dorsal to the marg<strong>in</strong> <strong>of</strong> the foremost part <strong>of</strong> the chiasma, separated, however, from it by the tractus isthmo~optieus (figs. I, 2, 3, 4). <strong>The</strong> major axis <strong>of</strong> th is ellipsoidal body extends <strong>in</strong> a transverse plane from ventromedial to dorsolateraI. and is but little longer than the longer <strong>of</strong> the m<strong>in</strong>or axes, whieh is directed sagittally. <strong>The</strong> third axis is considerably shorter than the other two. <strong>The</strong> <strong>nucleus</strong> <strong>of</strong> <strong>BELLONCI</strong> lies dorsolateral to the volum<strong>in</strong>ous cell group, mostly designated without specifieation as lateral genieulate, but whieh I agree with KUHLENBECK (1937) <strong>in</strong> regard<strong>in</strong>g as the ventral lateral geniculate (figs. I, 3). This <strong>nucleus</strong> beg <strong>in</strong>s a little more caudally than the <strong>nucleus</strong> <strong>of</strong> <strong>BELLONCI</strong>. Just <strong>in</strong> front <strong>of</strong> the latter the <strong>nucleus</strong> supraopticus and <strong>nucleus</strong> <strong>of</strong> the diagonal band <strong>of</strong> BROCA are situated, the former ventrally and applied to the optie tract, the latter more dorsally (fig. 4). <strong>The</strong> <strong>nucleus</strong> <strong>of</strong> <strong>BELLONCI</strong> is immediately succeeded by the <strong>nucleus</strong> rotundus (figs. 3, 4). <strong>The</strong> ramus dorsalis <strong>of</strong> the tractus septo~mesencephalieus courses dorsal to the <strong>nucleus</strong> <strong>of</strong> <strong>BELLONCI</strong>, so that it is wedged <strong>in</strong> between this tract and the tr. isthmo~optieus (figs. I, 2, 3, 4) . Though closely applied to these tracts, so that it may synapse with them, there is no conclusive evidence, <strong>in</strong> our WEIGERT-PAL preparations, <strong>of</strong> such a supply, no more than by the optie tract. As far, however, as it is possible to judge from WEIGERT PAL preparations, the chief supply <strong>of</strong> the <strong>nucleus</strong> <strong>of</strong> <strong>BELLONCI</strong> is provided
1095 tr. sept~mesel1e ventr. I at .,.........~"""'-':..:...""".' . : . Idl"Yl. hyper5lr:- ~. , i'< tlucl . sept~hipp.--,'......".~,..-;...;.---",-* Jam.med. tr. cori-; hab. lat. ant. -fr. front,a r! neostr. p. m h. sept~ mes en rdm . dor.s. rec. , pra dec. supraopt. • V. p.v. l'Iud. <strong>in</strong>terC.lam . 5upr. ", 11 11 11 Suphyperstr. dors. h~perstr. ventr.p.d. ,. fI 'I v. dm. hypersi:r. he 0 str. <strong>in</strong>term. ~~~~~+'~:-'7,\",c
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