Article beginning on page 340.
Psyche 3:340, 1880.

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ASYMMETRY OF THE NERVOUS SYSTEM IN THE LARVA OF HASP YIA.
BY ANNA EATHERINA DIMMOCK, CAMBRIDGE, MASS. NOTHING has been published in regard
to asymmetry of the nervous system of
arthropoda, as far as I have been able
to ascertain.
In dissecting a number of the larvac
of ffarpyia (Bonibyx) vinula, I found
that the nervous system, instead of ex-
tending in a direct line in the ventral
region of the larva, as is common in in- sect larvae, curved outward laterally
between the first and second thoracic
ganglia, as seen between c and d in figure 6. This curving, which was toward
the left in six larvae examined, is to
avoid interference with the duct from a
sac, or gland, which opens out between
the first and second thoracic ganglia.
This gland, represented in the figure by a dotted line, secretes a liquid, said to contain salicylic acid, which the larva
ejects, as a means of defense, when clis- turbed. The duct of this gland opens
by a transverse cleft, figured by Muller,l on the ventral side of the first segment posterior to the head. Farther details
in regard to this gland are unnecessary
as a good description of it has been
given already by Rei~gger.~
In the earlier stages of the larvae of
Harpyia, the nervous system turns con-
siderably out of the direct line, in order to allow the duct of the gland to pass,
I 0. F. Miiller.
Pile-Larvcn mod dohbelt Hale, og
dens Phalacne . . . Kjobcnhavn, 1773, pi. 2, fig. 3, d. 2 J. R. Render.
Physiologische Untersuchungen
fiber die thierische Haushaltung dcr Insecten. Tiibing-
as can be seen in figure 6, which reprc- sents the condition in a half-grown
larva; but, in the full-grown or nearly
full-grown larvae, the nervous system is nearly straight, altho it is still distinctly unsymmetrical. This lessening of
asymmetry, as the larva grows, is due
Fig. 6.-View of anterior portion of central nervous system of larva of Harpyia vinula as seen from above : a, snpraoesophageal ganglion ; b, infraoesophrtgeal &nglion; c,d, and e, thoracic ganglia;/, first abdominal mnglion. Dotted line represents gland mentioned in text. Enlarged 6 times.
to the duct being somewhat smaller in
larger larvae, in proportion to the size of the larva, thus allowing the nervous
system to settle back, more or less, into its normal position.
The comtnissures connecting the first
and second thoracic ganglia
(c and d)




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length, aqiftrating at the posterior fourth pgkt has been I'onnd, ay far as 1 to admit the passage of muscles which in no other arthropod, Init, upon sugges- are described later. The united coin- tion of Professor Leuckart, of Leipzig, missures are slightly enlarged po~terio~ in whose laboratory I was studying when
to the first thoracic ganglion {c). I discovered the asymmetry in the ner- fhe muscles which cross each other voua system of the larva of Haqyift, 1 between the eomrnissorea connecting the examined fffrudo medicinalis, the first and second and second and third blood-leech, the nervous system of which thoracic ganglia ore generally found in has an analogous a lepidopterous larvae, auci serve to hold ital organs are Ì the second and third thoracic ganglia in Himdo. as to necessitate the median line. The mode in which of the newoil these muscles cross each other and inter- aide, tiear their outlet lace the cornmissures, as seen in the fig- Of four specimen we, is the same between the second and ined. two had third as between the first and second right and two thoracic ganglia. This mode of inter-
organs ; hut of six s
lacing of the muscle,'? atid commissures dissected, all is exactly the same in the larva of Sphh tween the first and second thoracic gan- ncellda as it is in that of Harpyia. glia deflected toward the left. The kind of asymmetry existing in
the nervous system of the larva of ffw-
p"r<'s* 3 Dpr. i8Si+
S t'f'h: O S PA I TO(? Kyi X It [,vIfTl 'S. in <;l<IUtKK l>Y#Ìö14U'Ìö ~'Ailltit[Ili;K, MAS?. IN the winter of I fW-1 H79 I received,
made its iippearancc h flit- cavity of the from Stiffleld, Conn., a lot. of nearly wood, in which the pupa was confined. full-grown larvae of BlapliWnn fiaritfi~7- As the papa seemed in no way injured vm in twigs of .011ryt d6a. One of' I could not determine whether or not t h ~ these larvae, in a portion of a twig split larva had hatched from an egg within the it1 two parts which were carcfnlly and pupa. This larva was shown at th tiglit1y held together by a rubber band, 58th meeting of the Cambridge entorno- was reseryert upon my writing-toble for
logical chib. It was then very small and the purpose of taking notes on its trails- hsid the appearance of being lepidopte- fonnationa. This larva pupated in the ihons. Supposing it to he the larva of early part of
March, awl was then in some kind of museum pest that had, in tin apparently healthy condition. a mysterious way. gained access to the A short time titter the larva of El(#- pnpa, I took no description or figure of phidim bad pi~pat~vl, n small white lanv it. It grew slnwly, dwotiritig the pup



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