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May, 
NOTES. 
Herr Hans Gadow, in a memoir on the colours of feathers 
(“ Proc. Zool. Soc.”) divides them into three classes 
1. Objective, chemical colours, due to a black, brown, red, 
orange, or yellow pigment. 
2. Objective colours depending on structure. The feathers 
may either contain (a) no pigment, and the colour depends en- 
tirely on structure, — e.g., white, and sometimes yellow, — or (6) 
the feather contains a yellow or brown pigment, and the green, 
blue, or violet colour is produced by a peculiar transparent layer 
between the pigment and the surface. Of the non-iridescent 
colours blue and violet always depend upon structure. Green is 
derived from the refraction of a yellow pigment. Green pigments 
have been found very exceptionally. 
3. The iridescent colours are produced by transparent sheaths 
which act like prisms. 
According to M, Meyer the colour of distilled water, if viewed 
in a horizontal glass tube 7 metres in length, is of an intense 
blue by daylight, but by gaslight of a green. 
M. Pasteur has studied the pneumo-enteritis of pigs, which 
has carried off during the last year more than 20,000 swine in 
the Valley of the Rhone. He traces the affection to microbia, 
much smaller than the bacilli detected by Dr. Klein. 
According to the “ Gazette Hebdomadaire de Medecine ” a 
man living at Cuantla, in Mexico, is suffering from an anomalous 
disease in which the skin falls off in large patches. His sister 
died lately from the same affection. The malady is locally attri- 
buted to the circumstance that their mother ate largely of the 
flesh of the rattlesnake. 
It appears that Leonardo de Vinci studied the transmission of 
sound, and observed that if the bell of a trumpet was immersed 
in the water of a lake, and the ear applied to the mouthpiece, the 
noise of boats sailing at a great distance could be distinctly 
heard. 
Dr. F. L. Oswald (“ Popular Science Monthly ”) contends, in 
opposition to Buckle, that fanaticism is not the result but the 
cause of ignorance. 
According to M. Ch. Montigny (“ Bulletin de l’Academie Roy. 
Belgique ”) the twinkling of the stars is much intensified during 
