EMOTIONS. 343 



cially imitate the stimulus which the head of one caterpillar 

 supplied to the tail of the next in the series (and which 

 serves to let the latter known that the series is not inter- 

 rupted), I removed the last member of the series. As always 

 happens when this is done, the next member stopped, then 

 the next, and the next, and so on, till the whole series were at 

 a halt. If I had now replaced the last member with its head 

 touching the tail of the penultimate member, the latter would 

 again have begun to move, then the next, and the next, and 

 so on, till the whole, series would again have been in motion. 

 Instead of doing this, however, I took a camel-hair brush and 

 gently brushed the tail of the then last member. Imme- 

 diately this member again began to move, and so set the 

 whole train again upon the march. But in order that the 

 march should continue, it was necessary that I should con- 

 tinue brushing the tail of the last member. Now I found 

 that if I brushed in the least degree too hard, so as not suffi- 

 ciently well to imitate the stimulus supplied by the hairy 

 head of a caterpillar, the animal became alarmed and threw 

 itself upon its side in the form of a coil. I therefore tried 

 the experiment of puzzling the animal, by first brushing its 

 tail gently for a considerable time — so that it should have no 

 reason to doubt, as it were, that I was a caterpillar — and 

 then beginning by degrees to brush it more and more strongly. 

 I could then see that a point came at which the animal Mas 

 puzzled, so that it hesitated whether to go on or to throw 

 itself upon its side. It appeared to me that at this point the 

 animal began to become alarmed; for the brushing was still 

 exceedingly gentle, so that if the animal were actuated only 

 by a pun' ivtlcx mechanism, I should not have expected so 

 iiilinitesimally small a difference in the amount of stimula- 

 tion to produce so great a difference in the nature of the 

 response. 



in all particulars. I am likewise nhle to confirm all Hie other points in his 

 aOOOUnl i>t' the remarkable habits of these larva'. 1 may add that :is soon as 



■ member of a moving chain is removed, the next member in advance not 

 onlj itopa, bill bagini to wag its bead in ■ peculiar manner from aide t<> side. 



'1 Ins perhaps may serve :[ s a -i^nal to i he next member to — i < * i ► ; but» however 



tins may l»-. as soon as tlie ne\l one <|,„-s ttOU, it also begin! to Wag Ltl head 



in tin- same manner, and so on till all the caterpillar* in advance of the 

 interruption are itanding still and wagging their bead*. And they all 



Continue without interruption thus to wiig their heads until t he prOOMUi in 



again begini to mora I hive oererMen thi^ peculiar moremenl performed 



except under these cireuiuatuucc*. 



