Thompson — Degenerations from Lesions of I'emiooral Luhe. 197 



Monahoiv found stich fibres descending from the occipital lobe, and 

 entering both upper and lower fillets. The fibres in my own experi- 

 ments also occupied both these, though they chiefly lay in the upper 

 fillet. 



Bechterew,^ JEdinger,"^ Ohersteiner and Hill,^ Hosel,'^ Ferrier and 

 Turner^ also adopt the view of cortico -mesencephalic fibres. 



The fibres thus found in both fillets were never very numerous. 

 They were traceable as low as the pons, diminishing on their way 

 downwards, and no doubt ended in tegmental grey matter at succes- 

 sively lower levels, probably furnishing cortical connexions with the 

 nuclei of sensory cranial nerves. 



Thus throughout the whole chain of communicating links, a 

 bilateral plan of connexion seems to be followed. One would almost 

 a priori expect this. Moreover, it is interesting to note that this 

 system of " sensory" communications has its homologue in the mode 

 of termination of motor paths as Muratoff,^ Sherrington,'' and Melhis^ 

 have all shown. These observers have found that the portion of the 

 pyramidal tract destined for the lateral column when it reaches the 

 medulla, and rises dorsally prior to decussation, divides into two 

 portions ; a larger which crosses over into the lateral column of the 

 opposite half of the spinal cord, and a smaller which is continued on 

 into the lateral column of its own side. It is, I should ventru'e to say, 

 quite likely that the direct pyramidal bundle also ends bilaterally. 

 The manner in which the optic tract terminates in both retinae is not 

 without interest to call to mind in this connexion. Since I have no 

 doubt that the same rule applies to other areas of cortex than these 

 of the temporal lobe, one might therefore formulate a law of hilateral 

 connection hetioeen a given portion of cortex, and all the more distantly 

 situated masses of grey matter with which it is associated. 



1 Bechterew, " Untersuchungenu. die Schleifenschicht." Yerh. d. konigl. sachs. 

 Gesellsch. d. Wissensch. z. Leipzig, 1885, i., ii., s. 241-244. 



"^ Edinger, Vorlesungen iiber d. Baud. Nerv. Centralorg., s. 415 e^*" Aufl. 

 Leipz. 1900. 



^ Ohersteiner and Hill, Anat. of the Cent. Nerv. Organs (Lond. 1890), p. 252. 



* Eosel. " Beitrage z. Anat. d.JSchleifen." Neurol, centr. 1894, p. 646-549. 

 , 5 Ferrier and Turner, op. cit. 



* Muratoff, " Secund. Degener : nach Zerstorung d. Motor-Sphare des Gehirns, 

 &c.," Archiv f. Anat., 1893, s. 97. 



"^Sherrington, "Note on Experim. Degener. of Pyramidal Tract.," Lancet, i, 

 1894, p. 265. 



8 Melius, " Prelim. Note on Bilat. Degener. in the Sp. Cord of Monkeys 

 (Macacus Sinicus)," Proc. Eoy. Soc. Lond., LV (1894), p. 208. 



E.I. A. PROC, SEE. III., VOL. VI. P 



