142 Visuo-Sensory and Visno-Psychic Areas [CHAP. 



in the light of my researches on cortical structure it seems likely that these fibres bring 

 into relation the visuo-sensory and visuo-psychic areas. 



A similar function might be ascribed to (3) the fasciculus occipitalis transversus cunei 

 of Dejerine, and (4) the fasciculus occipitalis transversus gyri longitudinalis of Vialet and 

 Sachs, which seem to connect the cortex of the upper and lower lips of the calcarine fissure 

 respectively, with that of more outlying fields of the occipital cortex. 



(5) The fasciculus occipitalis verticalis or perpendicularis of Wernicke stratum proprium 

 convexitatis of Sachs lies beneath the cortex on the lateral surface of the lobe, and is 

 said to unite the gyri above with those below, but as a matter of fact the definition of 

 this band is difficult, and we cannot attach much importance to it. 



Passing next to the long association neurones, three bands call for special mention, the 

 fasciculus longitudinalis superior, the fasciculus longitudinalis inferior, and the tapetum. 



1. The fasciculus longitudinalis superior fasciculus arcuatus of Burdach is a bundle 

 of fibres lying lateral to and above the other long occipital bundles, which, according to 

 Dejerine and others who have attempted to trace it, connects the. occipital with the frontal 

 lobe ; but as in its course forwards it is constantly giving off and receiving fibres and at 

 the same time is a difficult bundle to follow, it is impossible to make any positive decla- 

 ration about its associations and functions ; I may mention, however, that it is supposed 

 to make connections with the auditory area in the temporal and with the motor speech- 

 centre (Broca's convolution) in the frontal lobe. 



2. The fasciculus longitudinalis inferior stratum sagittale externum (Sachs) faisceau 

 sensitif (Charcot) constitutes a uniting band between the occipital and temporal lobes. 

 Running in a sagittal direction, it lies lateral to the optic radiations, and in the first part 

 of its course is a massive and well-differentiated bundle, but more anteriorly its fibres 

 become confused with those emerging from the internal geniculate bodies, and with others 

 in the thalamic region. However, it is the general belief that the majority of its fibres 

 terminate in the temporal lobe, particularly in the first temporal convolution ; it is an 

 equally general assumption that it constitutes the main path of association between the 



' visual and auditory areas, and that its destruction lies at the bottom of that variety of 

 mind blindness which we have referred to under the name alexia. But here let me say 

 that Flechsig dissents from the general belief, contending that the bundle consists of 

 projection and not association fibres. 



3. Opinions seem to be divided concerning the tapetum. For long it was regarded as 

 a part of the radiation of the corpus callosum, but since it has been found to be perfectly 

 preserved in cases of congenital absence of this body, that view has to a large extent 

 fallen to the ground, and Fovel, who has given one of the best reports of a case of this 

 deformity to be found in the literature, thinks that the tapetum pertains to the fasciculus 

 longitudinalis superior. Dejerine, on the, other hand, to whom we must pay respect as an 

 authority in this province of cerebral anatomy, considers that the tapetum is a perfectly 

 independent sagittal fasciculus, pertaining neither to the corpus callosum nor to the fasciculus 

 longitudinalis superior, but arising from the cortex of the frontal lobe, and after passing 

 through the corona radiata, being distributed over the lateral surface and inferior border 

 of the occipital lobe. Having these views concerning its origin, course, and destination, 

 Dejerine reasonably prefers to call it the fasciculus occipito-frontalis. 



