50 SCIENCE FROM AN EASY CHAIR 



alarmed by it. This is the little green tree-frog, Fig. i, 

 which now comes forth from its winter sleep, and assembles 

 in thousands guided by the " croak " or " call " which is 

 produced by the males. The females have a very small 

 voice comparatively. I kept two a male and female 

 through a winter in London, and when the spring came 

 the male terrified the household one night by unexpectedly 

 uttering his cry loud and sharp to which the female 

 replied. "Wharr! biz" is the nearest expression I can 

 give in letters to the two sounds. After a great many 

 evenings spent in these rhythmical declamations, the little 

 frogs collect round pools and tanks, and at last drop from 

 the trees into the water, and there deposit their spawn. 

 When producing his cry the male distends the skin of his 

 throat like a balloon. The air is driven alternately from 

 it into the lungs and back again over the vocal chords, 

 which vibrate with no uncertain sound. These little frogs 

 are easy to keep in an inverted bell-jar or in a fern-case, but 

 must be fed regularly with flies and spiders, which they 

 catch by a sudden dab of the tongue at the moment of 

 alighting from a long leap on to the glass where the insect 

 is crawling. They can hold on to smooth glass or leaves 

 by means of their sucker-like toes (Fig. i). 



The colour of the upper surface of the South European 

 tree-frog is a most vivid and smoothly laid-on grass-green. 

 Occasionally the colour becomes altered to a brownish 

 purple, but returns after a day or two to its usual bright 

 green tint. A great rarity is the blue variety of this frog 

 the enchanted Prince of the Cote d'Azur blue as the 

 sky and the sea around him the true genius loci. I 

 obtained one a few years ago at Mentone, and kept it 

 alive for three years in London. Its blue was the blue of 

 the forget-me-not or the finest turquoise. When it died 

 (I believe of old age, and not from discomfort or disease) 

 I examined its skin very carefully with the microscope 



