The brain of Acipenser. 243 
25) The minute structure of the corpus striatum was completely 
described in my preliminary paper. The epistriatum serves both as 
an olfactory center and as a coördinating center for sensory tracts 
ascending from the hypothalamus. It transfers impulses by short 
neurites to the striatum. The striatum sends its fibres to the ‘tween 
brain to make connections with descending or motor paths. 
26) The olfactory area in Acipenser includes nuclei near the 
olfactory lobes and the nucleus taeniae in front of the chiasma. 
All these nuclei send fibres to the ganglia habenulae and the hypo- 
thalamus. These nuclei are not to be compared in any way with 
the cortex of higher forms. 
27) There are found in Acipenser two sets of cells which seem 
to constitute the earliest representative of the cortex proper. One 
of these serves to connect the epistriata of the two sides by fibres 
through the anterior commissure. The other is found in the dorsal 
membraneous roof of the fore brain and probably corresponds to 
the dorsal or dorso-median cortex of Reptiles. The transformation 
of a fnembraneous pallium into a massive, nervous pallium which 
has recently been declared impossible is seen in actual progress in 
its early stages in Acipenser. 
28) The olfactory commissure is in part fused with the anterior 
commissure but is in part separate. 
29) The olfactory lobe contains, besides large and small mitral 
cells, several varieties of cells which have the same functions as the 
mitral cells. These are probably to be homologized with the granule 
. cells of higher Vertebrates. There are in addition cells of the II type 
and cells like the cells of CayAL in the cerebral cortex of Mammals, 
the function of which is unknown. 
30) It is desirable that the brain should be described with 
reference to longitudinal zones in the manner attempted by Burcx- 
HARDT (94). Such a division into zones must rest, however, on the 
most complete possible knowledge of the minute structure and con- 
nections of all parts of the brain. Our knowledge is not yet full 
and accurate enough for this purpose. The treatment of the sensory 
centers in the medulla and their relations to the cord and cerebellum 
given in the present paper, may be regarded as a contribution to 
this end. 
Morgantown, W. Va., 
August 21, 1900. 
16* 
