1896.] “ Mushroom Bodies” of the Hexapod Brain. 647 
importance to phenomena that are relatively unimportant, and 
has resulted in a somewhat misty conception of the structure 
of the hexapod ventral nervous system. 
One of the very first things that an impregnation of bee 
brains with bichromate of silver enabled me to make out was 
the structure of the mushroom bodies with their cells. These 
cells stand out in sharp contrast to all other nerve cells known, 
though they recall to some extent the cells of Purkinje in the 
higher mammals. Each of the cells contained within the 
fibrillar cup seeds a nerve process into the later, where it 
breaks up into a profusely arborescent system of brahchlets, 
which often appear with fine, short, lateral processes, such as 
are characteristic of the dendrites of some mammalian nerve 
cells. Just before entering the fibrillar substance a fine branch 
is given off that travels along the inner surface of the cup 
along with others of the same nature, forming a small bundle 
to the stalk of the mushroom body, down which it continues 
until it reaches the origin of the anterior and the inner roots 
mentioned at the beginning of the paper. Here it branches, 
one branch continuing straight on to the end of the anterior 
root, while the other passes to the end of the inner root. 
Throughout its whole course the fiber and its two branches are 
very fine. Nearly the whole stalk and nearly the whole of each 
root is made up of these straight parallel fibers coming from the 
cells within the cup of the mushroom bodies. What other fibers 
there are enter these bodies from the side, and branch between 
the straight fibers very much as the dendrites of the cells of 
Purkinje branch among the parallel fine fibers from the cells 
of the granular layer in the mammalian cerebellum. These 
fibers are of the nature of association fibers. : 
From the olfactory or antennal lobe, from the optic ganglia 
there are tracts of fibers that finally enter the cups of the mush- 
room bodies as shown by Viallanes and by my studies with the 
Golgi method and also with a Formol-copper-hematoxylin 
method of staining. Besides these tracts the Golgi method has 
enabled me to make out another tract, unknown before, passing 
down the hinder side of the brain from the cups to the region 
above the cesophagus, where it bends forwards and comes in 
45 
