HERPETOLOGY OF THE GRAND DUCHY OF BADEN. 385 



dead leaves, &c, it assumes a variable protective resemblance to 

 the surroundings. The chromatopheres are also very susceptible 

 to atmospheric changes. 



Several writers have observed a tendency to blue coloration 

 in this species. I obtained an interesting variety of this nature 

 near the village of Forchheim, in a pond in the Ehine woods : 

 the darker markings on the back were perfectly normal, but the 

 green, instead of displaying the yellow fundamental hue, was of a 

 verdigris tint, imparting to the frogs a most curious appearance. 

 I forwarded some of these to Prof. Leydig, who said that the blue 

 colour had not been affected by the journey, but that the day 

 after (having in the mean time assumed a "dark-blue" tint) 

 they were transported in a sack for a short distance, and on 

 being suddenly exposed to the full sunlight the colour rapidly 

 changed to a " light-bluish white." This was due to the con- 

 traction of the colour-cells ; at the same time he considered that 

 there must have been some permanent modification to produce 

 the original blue colour. I observed this singular variety for 

 three consecutive years at the same locality. The peculiarity, 

 though commoner to the female sex, was exhibited equally 

 strongly by some males, and as other specimens of both sexes 

 showed no traces of it, I should be disinclined to attribute it to 

 the influence of purely external circumstances. 



The other variations in colour are produced by the various 

 shades of the fundamental tint, or by the accentuation of the 

 three light-coloured bands on the back. As a rule, the dorsal 

 one is the most pronounced ; at other times this is nearly effaced, 

 and the lateral row of pores becomes prominent. A male variety, 

 not rare in the Ehine district, has the head of a nearly pure 

 gamboge colour, as well as a small patch of the same colour on 

 the throat. The yellow pigment on the flanks and hind legs 

 varies considerably in degree. 



As naturalists experience some difficulty in catching sufficient 

 numbers of this frog, owing to its extreme wariness and swift 

 movements, I will describe a method of capture which far super- 

 sedes the unsatisfactory one usually employed. The intending 

 angler, having attached a small piece of red cloth by way of 

 bait to his line, must hold this touching the surface of the water. 

 He will be astonished to see the frogs (especially in the spring- 

 months) wildly endeavouring to seize it, and literally struggling 



