REACTIONS OF LAND ISOPODS TO LIGHT 



227 



Apparently the unnatural condition of being submerged in water 

 made them indifferent to light. 



This change from a negative reaction to indifference corre- 

 sponds to the changes found by Holmes, in that normal photo- 



Number of 



N«6»ti«e 



Q Gradc-s of 



Ne^atiueT\eSS 





Cr 



8 ■ 



1 z 



5- 



N«^Tiy 



8 Grddes of 

 Ne^at>veT\ess 



Figs. II and 12 Comparison of reactions after exposure to a minimum and 

 maximum of environmental moisture. Fig. II, Oniscus; Fig. 12, Porcellio scaber. 

 Numbers on abscissae indicate grades of negativeness shown in figure 2. Num- 

 bers on ordinates indicate number of responses in each class. Fig. 11 shows 

 practically no difference between the responses of Oniscus under the two con- 

 ditions. Fig. 12 shows a slight difference in Porcellio under the two conditions, 

 the animals being less negative after living in a dry habitat. 



