308 



MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 



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

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



The form of the mushroom body is much more complicated in the bee or ant than in insects of other orders. 

 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 different 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 apiily 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 ft-ora 

 Viallanes (Figs. X, XI), tliat tlie nmsliroom bodies, tliongh 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 



loc.rt 





Fig 



TraD.sverse section tbroagh the brain of the locust ((Edlpoda and 

 C'aloptenus) -.C, lower part of c, calyx, of musbroom body ; s(, stalk of the 

 same ; 6, pel, bridge of the protoc^robral lobes ; mo, nerve of median 

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

 region of the central body ; tcb, tubercle of the central body ; /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 ; i(, trito-cerebral lobe; ffcld, gc, ganglion cells After 



oe.com 



laLir f/ 

 tr.conv 



Fig. XI. — Sagittal section through the bram of the locust; I. 

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

 dunculated body; it, internal tubercle of the pedunculated 

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

 1, commissural cord ; c. an. I., cortical layer 

 ■ lobe ; cmol, central mass of the olfactory 

 lobi'; "i ".- /, IiIh I, uniting the median lobe of the middle 



prcit.i.i . is;il lobes of thedeutocercbron; <7c., 



trit. I. _ I . I .1 i.rii-s of the trito-cerebral lobe; gan. 



i, cort. \ oi ,uin mill ii.ifjictory) lobe; lab.fr, labro-frontal 

 nerve ; op. fnm, n-sopbagoal commissure ; tr. com, transverse 

 commissure of oesophageal i^g ; other letters as in Fig. 

 X After Viallanes. 



of the 



of the ca])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 th» brain. But in Limulus the ma.sscs of aprotoplasmic 

 cells, with the fibrilhe arising from them, constitute nearly the lower half of the entire brain, licsjdes 

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

 Viallanes himself declares, ,^0 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 poi'tion 

 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 from what we have variously 

 called the chromatit; or aprotoplasmic, or small ganglion cells, and in part fi'om what we call the 



* This is somewhat of an exaggeration, and -1^°,,- would seem to be nearer the correct proportion 



