98 Dr. A. Hill. The Fasciola Cinerea ; its Relation [May 2, 



limb.* Such results may, as the authors say, be considered to point 

 to the " profound difference between the production of the fine move- 

 ments of the limb in volition, on the one hand, and by experimental 

 stimulation of the cortex, on the other." This explanation is as valid 

 for tbe one as for the other interpretation. 



The stimulation by electricity may, and probably does, involve a 

 very different kind of stimulus from that which normally emanates 

 from the cortex during a voluntary act, and how subtle are the 

 differences that exist between the conditions leading to paralysis or 

 not in different instances may be judged from the functional cases of 

 paralysis of cerebral origin, previously referred to, in which there 

 may be in the same person, in immediately successive periods, com- 

 plete paralysis of the limb so long as the eyes are closed, and no such 

 paralysis when the eyes are opened. 



What has been said above shows, moreover, how much removed we 

 are from the position assumed to be true about twenty years ago,t 

 when centres " immediately concerned in effecting volitional move- 

 ments" were considered to be " as such truly motor." 



IV, " The Fasciola Cinerea ; its Relati6n to the Fascia Dentata 

 and to the Nerves of Lancisi." By ALEX HILL, M.D., 

 Master of Downing College. Communicated by Prof. A. 

 MACALISTER, F.R.S. Received April 2, 1895. 



In my paper on the hippocampus, published in the Philosophical 

 Transactions of the Royal Society for 1893 (vol. 184, B, pp. 389429), 

 I stated as a subsidiary conclusion, resulting from my investigation of 

 the brains of marine mammals, that " there is no reason for associating 

 the fascia dentata with the striae longitudinales (nervus Lancisii), 

 gyrus supracallosalis, and gyrus geniculi, or for supposing that all 

 these four structures belong to a single organ, which forms a part of 

 the cortical centre for the sense of smell." 



This conclusion was based upon the following observations : A. In 



* This fact shows that the cutting off of the afferent impressions by section of 

 the sensory roots does not entail a lowered excitability of the kinaesthetic centres 

 in the cortex, but rather the reverse, if we look to the really lowered activity in 

 the spinal centres which the absence of tonus implies. In the case of complete 

 cerebral hemiansesthesia, however, there is, over and above the absence of any such 

 lowered activity of the spinal centres, another important difference between the 

 conditions existing and those which obtain in the experiments of Drs. Mott and 

 Sherrington, viz., no cutting off of cerebellar influence, so that the activity of the 

 cortex and of the sub-cortical centres is less interfered with. These differences 

 tend, I think, to explain the presence of paralysis with section of the posterior 

 roots, and its absence with cerebral hemiansesthesia. (May 4, 1895.) 



f Ferrier, " Functions of the Brain," 1st Ed., 1876, p. 200. 



