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case the original ventricle having been suppressed the neuroblasts are 
scattered within the substance of the organ. Elsewhere the karyo- 
kinetic figures are found only in the immediate vicinity of the ven- 
tricles in cells which adjoin the latter and lie between the ependyma 
cells. These neuroblasts are very numerous in the hypoaria which 
have not yet attained their definitive form. The cell-division is espe- 
cially rapid in the volvula and in the cephalic parts of the tectum 
adjoning the torus, a fact which tends to substantiate our theory that 
the torus is but a fold of the inner layer of the tectum. There are 
comparatively few nucleary figures in the cerebrum but the whole 
ventricular aspect is thickly crowded with newly formed cells. There 
seem to be special areas of proliferation in this region also. Enough 
is known at least to warrant the application of Prof. His’ theory of 
neuroblasts to the entire fish-brain. 
It seems that there can be no farther doubt as to the funda- 
mental homologies of the Teleost brain which in the ease with which 
fibres can be followed to actual connections with cells excells all other 
groaps. The application of metallic impregnation is here not only 
unnecessary but illusory for in the method suggested it becomes only 
a question of suitably orientated sections and uninterrupted series to 
follow any tract to its specific terminus and witness the union with 
the cells. 
It is a pleasure to acknowledge the assistance given me by Pro- 
fessor Frirsca and Professor HERTwIG as well as Dr. Benpa and 
other friends in securing the material and literature for these studies. 
Berlin, April 6 1892. 
