20 NCTvofii hvntui ; H»j«sK or touch. 



subdivisluiH (>r mattrr a-i cortAin portluii* (>r the nrrvuus Ryatcm do. Thus when U is sutcd 

 for th«? ftntt tltnr In our lirarine, thnt thv rye nf the eoninion hoiiw-fly is cr>ni|M>iin(le<l of 

 Bo l««^i thiui I'MM) xin^le ryr!«, it Mfm» liii|x>viil>ip that a niTve,<iriKinnlly tiiirrY>AC(>|>lr,can 

 be <iuUlivl<i<tl intii thriMil^ i-r ft!>rri •minricrilly thw to furni>!i ii rnrvo toearh simple eye ; 

 ami wh.-n w«< an- fiirlhtT lnf.'rm<-.i thiit the vyv of the <lrau<.n fly hai (21,000) >ix timi-a 

 M tunny Niit«.livl>»ii>nH us tJmt of thf hmiv lly, <.iir faith i?* >till luon- »evrr«')y taxi^i ; hut 

 to supix>s«« that a fliuim-nt Is wantini; in an eye, is t<> stij>iM»s<r that the «yr is made in vain ; 

 for the eyt' (le]ien<ls upon its nervous filament, however slender that may l>c, for its power 

 of vision. 



The srm|>athetir system i)f nerves in inseets has l)een Icnown fn-m the days of Swam- 

 MKHHAM, who rtrst disrovenil it in the rhin<»ceri>s Ix-itle. While this system is found mure 

 or less iK-rfiH-t in all artirulatjil animals, it is s|>ecially jMrficted in inseet?. The im|»«'rfee- 

 tioii-of tin- nervous ajipanitus consists in the aK^mceuf ih^ ctTtl'ml masses, or of all that 

 fiortion eoncerm-*! in the formation of idtus. N'othini; aj>|>ettrs in the nervous system of 

 the artieuUta, hi^her or aUive the Kan>?lionic c«'ntres which connect together tlu- double 

 ventral chonl. The ganglia of this system which ore more ]tarticularly devotetl Ui the 

 purely animal functions, undergo a slight chiuigc during the |)a»sage tntta the larval state 

 to that of the jHTfect ins«-ct ; the change c«>nsisling chiefly in a concentmtiou of nenroui 

 matt«r nixm thost- ganglia which are sul>s«'rvient to tin- function of hx-omotion. The hym- 

 imthctic sy-itmi, howi vrr, undergi-es no change : it is cipuilly i>erfect in the larva i'.s in 

 the mature animal, and reach<>s ils full development in this early stage of existence, then- 

 iiy showing that it presi»les over the functions of vegetative life. 



It is .scarcely nec»'ssary to sfieak more piirticularly of the functions of the nervous 

 system. It may, however, be obs4>rved, that it is uimui this .system that sensation depends, 

 and the nervous flbrils an- the channels thnuigh which the properties of external IxKlies 

 U-odne known to the iiidiviilual. If we may judge of c«u.s«>s by efleets, we are T\arranted 

 in lu'lieving that impressions an- receive<l by insects from without, in the same manner as 

 is the r«>M- with the higher animals; and that they fxissess nil thost- special st-UM-s which 

 belong to the latter, and some of them in much greater i><rf<>etion. 



Toixii. The s«>ns«' of touch in insi-ets, in cons»'<iuence of the har»l cf>vering of their 

 b<Hlies, must l>e C4infine<l to certain juirls. Tlios*- who have watche«l their motions are fully 

 convincAHi that the palpi are the organs in which this sens*' is concentrated, or in which it 

 exists in its gn-atest i>erfection. These organs are constantly applied by the in.s< ct. after 

 the manner of frrlrrs, Ui the external Ixxlies with which it comes in pmximity ; and they 

 ar«- well ndapt<-d by their structure to fulfil such a purpt>se, being flexible, and Airnihhrd 

 with a soft and delicate integument. 



