The Life of the Caterpillar 



lars' spines, these draw up their fore-part with 

 a jerk and as suddenly lower it again; and 

 that is all : the intruders forthwith decamp. 

 Nor do the latter seem to contemplate any 

 harm: they refresh themselves on the honey- 

 smeared strip, they come and go tumultuously. 

 Their short flights may land them, now in 

 one place, now in another, on the browsing 

 herd, but they pay no attention to it. What 

 we see is casual meetings, not deliberate en- 

 counters. 



In vain I change the flock of caterpillars 

 and vary their age; in vain I change the squad 

 of parasites : in vain I follow events in the 

 jar for long hours, morning and evening, both 

 in a dim light and in the full glare of the sun: 

 I succeed in seeing nothing, absolutely no- 

 thing, on the parasite's side, that resembles 

 an attack. No matter what the ill-informed 

 authors say — ill-informed because they had 

 not the patience to see for themselves — the 

 conclusion at which I arrive is positive: to 

 inject the germs, the Microgaster never at- 

 tacks the caterpillars. 



The invasion, therefore, is necessarily ef- 

 fected through the Butterfly's eggs them- 

 selves, as experiment will prove. My broad 



368 



