306 



MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 



mushroom bodies, form a characteristic portion of the brain of adult insects. They have not yet 

 been found to be present in the Synaptera, but occur in the larva», at least of those of most meta- 

 morphic insects (Lepidoptera and Hymeuoptera), though not yet foimd in the larvae of Diptera. 



Fia \T —Sect 



«(( 11 ir II i\ will 1 the top 



of till limu 1*. r s.lii 11 II 3,0. col., 



ont.rc ilyx of lift mu-.hTo,.n. l..i,l> The lighter 

 portions represent the iirmulo fibrous central part of 

 the brain, and the dark tht cortical ganglionic cells. 



Fio. VTI —Section through the brain of adult Cahiptmus spretue. passing 

 through the mushroom bodies, o.cal., outer calyx, centr. &., central body; 

 ant. I., antennae lobe; op, n., optic uerve; w, com. I,, cerebral lobe. 



I have found these bodies in the nymphs of the locust {Caloptenus spretus), but not in the embryo 

 just before hatching. They occur in the third larval or nymph stage of this insect, and iu my 

 essay I stated : " It i> e\ ident th it by the end of the first larval stage the brain attains the develop- 

 ment seen in the thud larv.il ^^t.ite ol the two banded species" (C. Uvittatua). 



Flo. Vin — Enlarged view of the trabecula ; 



s nerves, of the mushroom body, its caiict 

 the origin of the optic nerve. 



The result of my studies on the brain of the embryo locust was that from the "embryonic 

 cerebral lobes are eventually developed the central body and the two mushroom bodies" (p. 237). 

 Fig VI, copied from my essay (PI. xii, Fig. 1), shows the early condition of the mushroom bodies 



