18 .-i Reconstructlun of the Nuclear Masses in 



laterally from the central gray matter. The ventral margin lies in a straight 

 line, is straight along the central gray matter for the caudal one-third of the 

 nucleus; then it forms, in the deep groove filled with fibers of the fasciculus 

 cuneatus, between the gracile and cuneate nuclei, another straight line which 

 continues to the point where the two nuclei are closely related on the lateral 

 plate, above mentioned, as the nucleus of fasciculus gracilis curves medially 

 to terminate. 



Miss k^abin, in her reconstruction of the medulla and mid-brain of the 

 new-born, considers the gracile nucleus as a separate entity only in the 

 caudal portions, but as fusing above with the cuneate nucleus to form a 

 central nuclear mass a nucleus of the dorsal funiculus, which she believes 

 to be wholly a nucleus fasciculi cuneati. The nucleus of Blumenau she 

 considers as also contributing to this nuclear complex. While such a fusion 

 of the cephalic portion of the gracile nucleus with the cuneate nucleus could 

 be assumed, study of the serial sections in the adult has led to the conclusion 

 that the nucleus fasciculi gracilis can be divided from the nucleus fasciculi 

 cuneati. These limits of the nucleus fasciculi gracilis have already been 

 described for the adult. Miss 8abin's description of the morphology of the 

 nucleus fasciculi gracilis is somewhat inadequate, so that a close comparison 

 of the shape of the nucleus in the new-born and adult can not be made. 



NUCLEUS FASCICULI CUNEATL 



Beginning caudally somewhat superiorly to the mid-point of the decus- 

 satio pyramidum and extending cei)halad to the caudal limit of the cochlear 

 nucleus, the nucleus fasciculi cuneati presents a varied and irregular mor- 

 phology. In its longitudinal diameter the nucleus measures in this adult 

 medulla 14.4 millimeters; the other diameters are not given, on account of 

 their marked variation at different levels. In this study, account is taken of 

 the so-called nucleus cuneatus lateralis or the nucleus of Blumenau (1891) 

 that collection of well-defined large cells which overlies laterally the main 

 cuneate cell-mass. In the reconstruction it was found that these collections 

 of apparently isolated cells lying in the fibers of the fasciculus cvuieatus were 

 connected in every case with the main nucleus, so that a division of the two 

 nuclei could not be made except on histological grounds. Whether such a 

 division has any functional or neurological importance can not be ascer- 

 tained by the means of study used in this reconstruction. The two portions 

 of the nucleus have been modeled together and will be described as far as 

 possible as a single nucleus fasciculi cuneati. As mentioned in the descrip- 

 tion of the nucleus fasciculi gracilis. Miss Sabin included together the cephalic; 

 portions of the nuclei of the dorsal funiculus; this inclusion of the two in a 

 single cephalic enlargement we do not consider now justified. Tlie nucleus 

 fasciculi cuneati is easily differentiated from its neighboring nucleus of the 

 fasciculus gracilis. 



