CuRRAN, A New Association Fiber Tract. 651 



It was my intention at the outset in writing this paper merely to 

 report the discovery of a new or hitherto undescribed tract in the 

 cerebrum, but since the chief method of investigation used in this 

 research is not well known, I thought it desirable to delay the reader 

 with the foregoing description. It was in the practice of this method 

 while applying it to well-known structures in order to obtain a more 

 perfect knowledge of them that I frequently found a long associating 

 bundle of fibres uniting the occipital lobe with the frontal, and tak- 

 ing a course to the external side, and very close to the base of the 

 lenticular nucleus, and in immediate relation with the anterior com- 

 missure as it enters the temporal lobe. At first I was not inclined 

 to consider it as uniting the occipital with the frontal lobe, and 

 thought that it probably belonged to the lower horizontal fibers of the 

 external capsule. Subsequent investigation disproved this and 

 brought out its true nature- — that of continuous fibers uninterrupted 

 by nuclei at any place in its course. All the fibers of the external 

 capsule can be traced in gross dissection to their origin with perfect 

 distinctness, and there can be no false continuity of fibers because 

 they break off easily about their nuclei and the breaking off corres- 

 ponds with what one would expect from the microscopic appearance. 

 The' fasciculus occipito-frontalis described by Dejerine^ and others 

 takes a course widely different from that of this bundle. Although 

 authorities differ as to its exact location, all agree that as it passes 

 from the front to the back of the brain it is in immediate relation 

 with the corona radiata about or above the level of the highest point 

 of the lenticular nucleus. Some say that its fibers are among those 

 of the fasc. arcuatus (superior longitudinal bundle), which lies well 

 above the lenticular nucleus and to the external side of the corona 

 radiata ; while others place it to the inner side, in close relation with 

 the caudate nucleus (Forel). IvTo one has ever suggested that it takes a 

 course below these points. I have been unable to convince myself 

 that it exists as a continuous bundle in any of the positions men- 

 tioned. However, since the fasciculus which T am about to describe 

 lies, throughout the greater part of its course, in the deep white 

 matter of the temporal lobe, swinging well below the thickest 



*Anatoniie des Centres Nerveiix, 1905. 



