1897.] The Optie Lobes of the Bee's Brain. 375 
connect. In the bee it is situated outside of the outer of the 
two bodies that are connected. 
In summarizing the matter as just described, and as shown 
in my drawings and sections, it appears that, setting aside the 
outer or retinal elements, there are concerned in the trans- 
mission of visual stimuli to the central portion of the brain 
some six or seven neural elements, and that such stimuli 
may reach (1) the optic body, (2) the mushroom bodies, and 
(8) the hinder lower portion of the brain, and that they 
may pass over one or the other of the optic commissures— 
provided the upper one is a real commissure—to the inner 
fibrillar body of the opposite lobe, and thus indirectly reach 
the mushroom bodies, the optic body, and the posterior 
region of the brain on the opposite side. Further, it may be 
seen that there may be either three or four, or possibly more 
—but at least three—neural elements concerned in the trans- 
mission of a single stimulus. Thus, a stimulus may reach the 
optic body, the mushroom bodies, and the lower posterior por- 
tion of the brain as follows: 
The mushroom bodies, — 
By three elements, 1 a—2 b—(a.-s.ot.r.) or 
1 a—2 b—3 d. 
The optic body, 
By three elements, ~ 1 a—2 b—3 d. 
The lower-hinder brain, 
By three elements, 1 a—2 b—(a.p.t). 
By four elements, 1 a—2 b—3 d—(p.o.t.). 
Further it appears that a single stimulus might reach all 
three cerebral centers. 
This explanation seems to accord best with the existence of 
two sets of fibrillar branchlets upon one element (b.c. and d.e.) ; 
but it must be held to be hypothetical, since I have not been 
able to ascertain definitely whether the terminals of the fibers 
of the posterior, the antero-superior, and the antero-posterior 
optic tracts connect only with the secondary branchlets (c and 
e). If connections are made with the primary sets (b and d) 
then the matter becomes much more complicated. 
