308 



MEMUIKS OF THE NATIONAL ACADEMY OF SCIENCES. 



pia mater [neurilemma]. These convoluted bodies and the stalks upon which they are mounted are compared by 

 Dujaidin to certain kinds of mushrooms, and this idea has been retained by more recent writers on the subject." 



The form of the nuishroom body is much more complicated in the bee or ant than in insects of otlicr ord<rs. 

 In the cockroach and in other Orthoptera, notably the locust, the four divisions of the calices are united into two, 

 while the structure of the calyx in the cockroach is quite ditfcrent from that of the locust. Mr. Newton, in his 

 description, notwithstanding Dujardin's statement, appears to practically limit the term "mushroom body" to the 

 cap or calyx on the end of the stalk. In the following description we apply the term "mushroom body" to the 

 entire structure, including the base or trabecula, the double stalk, and the cap or calyx. (Pp. 231, 232.) 



It may be seen by reference to my figures and those copied from Newton (Fig. IX) and from 

 Viallanes (Figs. X, XI), tliat tlie mushroom bodies, though arising from about the middle and lower 

 third of the brain, are mainly contained in the upper region of the brain, this being the position 



Fio. X Transverse section through the brain of the locust (CEdipbtla and 



Caloptenus) : c', lower part of c, calyx, of mushroom body ; st, stalk of the 

 same; h,pcl, bridge of tlio protocerebral lobes: mo, nerve of median 

 ocellus; ch, transverse fascia of the optico-olfactorychiaama; feb, fibrous 

 region of the central body ; tcb, tul»ercle of the central body j /ch, descend 

 ing fascia of the optico-olfactory chiasma; choo, superior fascia of the 

 optico-olfactory chiasma; pt,pl, protocerebral lobes ; id, dorsal lobe of the 



deuto-cerebrum ; It, trito-cerebral lobe; geld, gc, ganglion cells After 



ViaUanes. 



can. I 



gan.!. 

 acunX- 



gc.tiit 



lah.fc 



oe.com 



tr.conv- 



FlQ. XI. — Sagittal section through the brain of the locust : I. 

 oc. n, lateral ocellus nerve ; at, anterior tubercle of the pe- 

 duncul-ated body ; it, intem.al tubercle of the pedunculated 

 body; cl, cerebral lobes; II, lateral lobe of the middle pro- 

 tocerehron; com, commissural cord ; c. an. Z., cortical layer 

 of the olfactory lobe ; cmol, central mass of the olfactory 

 lobe; ac. an. I, libers uniting the median lobe of the middle 

 protocerebron with dorsal lobes of the deutocerebron ; gc, 

 trit, I, gangliouated cortex of the trito-cerebral lobe ; g an. 

 I, cortex of antennal (olfactory) lobe; lab. /r, lahro- frontal 

 nerve ; oe. com, (esophageal commissure ; tr. com, transverse 

 commissure of cesophageal ring ; other letters as in Fig. 

 X After Viallanes. 



of the cai)S of the mushroom, or calyces, these in part, as in the figures of Viallanes, forming two 

 lobe-like protuberances (c, c'), the base of the stalk scarcely reaching the middle of the brain; in 

 fact, being confined to the upper third of the brain. But in Limulus the masses of aprotoplasmie 

 cells, with the fibrillie arising from them, constitute nearly the lower half of the entire brain, besides 

 forming a thick cortical envelope on the sides and in front and behind, and constituting, as M. 

 Viallanes himself declares, y^Jij of the whole brain*. I was led, therefore, to think that these struc- 

 tures were not the homologues of the mushroom bodies of insects, but rather the cortical portion 

 of the cerebral ganglia, with its lobules, besides forming a part of the cortex of the optic lobes; 

 all the fibrous or fibrillar portion of the brain being in part derived fiom what we have variously 

 called the chromatic or aprotoplasmie, or small ganglion cells, and in part fi'om what we call the 



• This is somewhat of an exaggeration, and yo";, would seem to be nearer the correct proportion. 



