peocp:edings of united states national museum. 225 



"A quantitative analysis gave the following figures, the process being 

 carried on with the greatest care: 



"The result proves that the liquid in question is a true milk, and that 

 this milk does not differ from that of horses in general, except by the 

 presence of a little more fat, which diminishes its density. Possibly 

 the predominance of fat is due to the fact that the milk remained a long 

 time in the mammse, and that the casein underwent a regressive change. 

 Otherwise it is a liquid almost entirely composed of olein." 



Subsequent to the time of this observation my friend, Mr. Epifanio 

 Jimenez, brought to Guanajuato a mule five years old, which gave about 

 a liter of milk daily for four months. The animal was taken away 

 again, however, so that I was unable to examine it. 



I have been made aware of an additional fact. I received milk from 

 two mules of the Hacienda de Luna, near Guanajuato, in February, 

 1880. It is salt, very fat, and whiter than that of which an analysis 

 has been given. The facts which I obtained are as follows : One mule 

 is fifteen years old, the other eighteen. The first furnishes milk at all 

 times of the year, and has done so from the time it was i^urchased. 

 The second mule has been nnder observation only a month. Neither 

 has given birth to young. The quantity of liquid given by the first 

 animal is 250 grams per day; by the second, a liter or a liter and a 

 quarter. 



Guanajuato, November 24, 1880. 



OIV I.AGOPUS MUTUS, I>EACH, AIVD IT.S Alil^IE!^. 



By I.UCIEIV M. TUR]\ER. * 



The following paper is based upon an examination of the specimens 

 contained in the National Museum collection, to which I have been kindly 

 allowed access by Professor Baird. A sufficiency of material alone can 

 demonstrate to a certainty the relationship of birds subject to almost 

 daily mutations of plumage as are exhibited in the various species of 

 the genus Lagopus. 



It is well known that individual birds of this genus differ greatly, 

 though they inhabit a restricted locality, such as a single mountain. 

 The birds from the lowlands are larger and have a looser plumage, 

 Proc. Nat. Mus. 82 15 July S9, 1 § 8®. 



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