(is CHARLES AY. HARGITT 



or deprived of the sense of sight, and placed in different con- 

 ditions of light, show the blind individuals to change color 

 much less rapidly." (p. 25). 



Biedermann also admits the influence of the nervous system 

 in relation to these changes, but holds it to be due to reflexes 

 other than visual, contrary to the view of Leydig who holds 

 with the foregoing to the direct influence of the visual reflex. 

 According to Biedermann it is perfectly easy to bring about 

 such changes of color by modification of conditions which affect 

 contact stimuli. For example, according to his experiments, 

 all that is essential in the case is that the surface be smooth or 

 rough, or that conditions which involve such sensation be in- 

 duced. This latter he held might be possible by section of 

 the nerves of the foot, or by drying the foot and thus disturbing 

 its normal sensory function. From experiments subsequently 

 described it will be noted that these views have not been con- 

 firmed . 



In my account of the many and varied experiments carried 

 on during March and April at the Naples Zoological Station, 

 I shall give in detail only those which have the most direct 

 bearing on the special problem of color change. Naturally I 

 was first concerned with those features which had been made 

 prominent by Biedermann, as mentioned above. Among 

 several kinds of cages or receptacles employed in the experi- 

 ments, only two were found generally useful, viz., glass jars 

 of some six liters capacity, and cages of wire gauze having a 

 zinc bottom to afford means of supplying needed moisture, 

 and a glass front to facilitate observation. Both were con- 

 venient alike for experiment and observation, but specimens 

 seemed invariably more at home in the jars than in the cages, 

 a matter of no small importance, and hence these were used 

 for the most part. 



Contact stimuli. As stated above, Biedermann has empha- 

 sized the importance of the nature of the stimuli acting upon 

 the sensory nerve endings of the toes as determining factors 

 in color changes in these creatures. It is in this way that he 

 explains the reactions following the introduction of leaves into the 

 vessel. " Wahlt man nur solche aus und bringt sie (in dunkeln) 

 in ein anderes Gefass mit Pflanzenblattern zusammen, so ergriint 

 die Haut in kurzester Zeit. Der Versuch gelingt auch mit 



