53 o THE POPULAR SCIENCE MONTHLY. 



In the skin of the chameleon he finds a close net-work of minute 

 ducts, connecting with pigment-vesicles situated on its under surface. 

 When the coloring-liquid is all retained in these vesicles, the animal's 

 skin appears yellowish, that being the color of the semi-transparent 

 epidermis. When the liquid is injected into the ducts, the color of 

 the animal changes, the tint depending on the degree of tension in 

 the ducts. If a nerve be cut, the region of the chameleon's body to 

 which that nerve was distributed becomes at once a deep black, and 

 no more color-changes occur over that area. If a piece of the skin be 

 placed under a microscope, it will appear black. Pass a current of 

 electricity through it, and there will be seen white vacuoles, which 

 coalesce into irregularly-shaped masses, and these in turn break up 

 into minute vacuoles again, leaving the field of a greenish color. Stop 

 the current, and the reverse order of phenomena appears. M. Bert 

 finds that the effect of curare on the chameleon is to give it a very 

 dark color, while chloroform, on the contrary, lightens the tint; but 

 when given in quantity sufficient to destroy the animal's life, chloro- 

 form darkens the color. Bert is disposed to believe that the chame- 

 leon possesses a special set of " color-nerves " distinct from the motor 

 and sensory systems, and that these nerves are under the control of 

 the will. 







THE ENGLISH OBSERVATORIES. 



TRANSLATED FEOM THE FRENCH, BY EMMA M. CONVERSE. 



THE English Astronomer Royal has in his possession a very cu- 

 rious collection of papers, including letters that have been ad- 

 dressed to him by persons of every condition, in which they ask his 

 price for casting a horoscope. In spite of such simplicity, England is 

 one of the countries where the taste for practical astronomy is very 

 widely diffused, and also the one where the greatest number of public 

 and private observatories is found. Establishments of the last cate- 

 gory abound in the United Kingdom, and attest by their number and 

 importance the popularity of the most sublime of the sciences. There 

 are at the present time forty observatories in the British Isles, and fif- 

 teen in the English colonies ; this is a quarter of the total number that 

 is found in the whole globe, for there are in Europe something like a 

 hundred and twenty establishments meriting this name, and about 

 two hundred in the entire world. 



The Royal Observatory of Greenwich takes the lead, for its past 

 labors as well as for its present position, over the other establishments 

 of the same kind possessed by the English. It was founded in 1675, 

 three years after the Observatory of Paris. Charles II. chose a locali- 

 ty for the edifice on a hill commanding the Thames and the passage 



