34 Annals Entomological Society of America [Vol. V, 
soft consistency of the alga did not offer the proper contact 
stimulus. 
There seems to be sufficient evidence that small objects are 
hot seen by the nymphs, for very frequently they will repeatedly 
ignore a particle of food held in their immediate neighborhood. 
This is also true of much fatigued specimens which, during their 
slow search for food, devour the savory morsels only when they 
accidently hit upon them. 
In another experiment I took ten specimens and placed each 
in a small dish of water containing a carefully measured piece 
of food. Daily observations were made and the results obtained 
are tabulated below. The (—) sign indicates that the food 
remained untouched; the (+) sign is meant to show that part 
of the food had been eaten, and (O) marks the day when no 
food remained in the dish: 
Specimen |Size of food | 1 PA Neve lh ee Gy | aye Ne 7h ll ks} | OF LON ate et 
1 1 sq.mm. : O 
PA SE Sec S=|=)S |S] =/-| oe 
3 ee Sef | | | 
4 25 « a fea) (a 
ag PAPREMES Spo |) 
6 35 « ih Rca ag ae +|0| 
RN Sat +/+{+]0] | 
8 ie an (ee ae ers 0 Se ole | a 
TTS e272 4) 0) | 
10 5.5 ee ee ee | 
The experiment was repeated with another set of nymphs, 
and similar results were obtained. Evidently the specimens 
in the first few cases did not see the piece of food, and ate it 
only when they came in contact with it by chance. 
THIGMOTAXIS. 
The strong positive thigmotaxis of the nymphs, as was 
stated in speaking of their habitat, is apparently the most 
pronounced feature of their behavior. When several specimens 
