ZOOLOGY. 293 



operator. At the time of writing his paper, he was employing virus 

 which had passed through twenty-five individuals. 



Instinct in Infusoria. Mr. H. J. Carlter mentions in the Annals of 

 Natural History (British) the following curious observation. He 

 watched an actinophorus rhizopod extracting starch grains from a 

 ruptured cell, looking like a spore ; the creature then retired some 

 distance off, and then returned, and although no more starch grains 

 were protruding, he contrived to extract some from the interior, 

 " This," he says, " was repeated several times, showing that the actino- 

 phys instinctively knew that these were nutritious grains, and that 

 they were contained in this cell, and that although each time, after in- 

 cepting a grain, it went away to some distance, it knew how to find 

 its way back." He likewise mentions the cunning of an amoeba, 

 which crawled up the stem of an acineta, and placed itself round the 

 ovarian aperture, so as to receive an infant as soon as it was born. 

 He observes, " that these facts evince an amount of instinct and de- 

 termination of purpose which could hardly have been anticipated in 

 a being so low in the scale of organic development." 



Material of Humming-Birds' Nests. It has long been a matter of 

 doubt as to what is the material of which the nest is made. It is soft, 

 white, cottony, homogeneous, and shingled on the outside with lichens ; 

 though evidently of vegetable origin, the precise material was not 

 known. In the Massachusetts nest, it proves to be the down which 

 protects the buds of the oak-tree in spring, and in this instance of the 

 red oak ; in the Georgia nest it was of a coarser character, but proba- 

 bly obtained from a similar Southern oak. Dr. Brewer, Boston Nat. 

 History Society's Proceedings. 



Mechanism of Locomotion. Prof. Marshall, in a recent lecture on 

 the above subject, before the Eoyal Institution, London, gave the fol- 

 lowing as the possible rates of animal locomotion per hour: shark 

 and salmon, sixteen and seventeen miles; flies, four to six miles; 

 eider-duck, ninety miles ; hawk, one hundred and fifty miles ; worms, 

 thirty feet ; race-horse, forty to sixty miles ; man walking, four to five 

 miles, running, twelve to fifteen miles. Especial attention was also 

 directed to the advantage of the atmospheric pressure on the joints, 

 amounting in the knee, where so much flexibility is required, to sixty 

 pounds, and in the hip-joint, to twenty-six pounds. 



Curious Observation respecting Yellow Fever. The late Major E. 

 B. Hunt, U. S. A., communicated to Silliman's Journal the following 

 curious observation respecting yellow fever, made at Key West : 



" On two separate occasions, when there were cases of yellow fever 

 in the U. S. Marine Hospital, which building I passed daily and saw 

 almost habituallv, I have seen a flock of buzzards, circlin^ over and 



v ' / ^5 



near the roof of the hospital by the hour together, and continuing this 

 day after day. I have never seen them do this except when there 

 were yellow fever cases in progress under the roof. So marked is this 

 fact as to have produced a common belief in town, that they only 

 hover over the hospital when there is yellow fever there. I am quite 

 persuaded that such is the fact, and* can only interpret what I have 

 myself seen as indicating that an odor is then thrown out on the air 

 which the keen scent of the scavenger bird detects from afar. The 

 material particles, whose diffusion is thus testified to, seem likely to 

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