SCIENTIFIC SUMMARY. 
683 
almost instantaneously, so as to give the fullest effect to the bird’s spring. 
The question naturally arises — how is this force to be suddenly applied 
without breaking or dislocating the animars legs ? The answer to this 
question is to be found in the peculiar character of the rectus femoris 
muscle, which binds down the patdlce, straps up the heel, and brings the 
whole machine into harmony at the moment that the spring is about to take 
place. The admirable mechanical economy of the leg of the ostrich may, 
says Professor Houghton, be illustrated by the parallel case of the Cornish 
pumping engine. “ Let us suppose a 100-inch cylinder engine about to com- 
mence its downward stroke, and to lift the pump-rods, weighing many tons, 
by means of a force of steam which commences at a maximum, and is 
gradually let off by expansion to a safe and manageable quantity. It has 
been found by experiment that it' is necessary to cause a minute vibration 
of the beam before letting on the full force of the steam, such vibration 
shaking all the nuts and joints into their proper places before the great and 
sudden action of all the parts takes place. If such a precaution were 
omitted, the sudden impulse of the steam would break the engine. In 
the leg of the ostrich, the rectus femoris supplies the place of the pre- 
liminary vibration ; it acts before the extensor muscles come into full play ; 
it binds down the two patellae, braces up the heel joint, and gives the signal 
for the gastrocnemido-solcBus, and other associated muscles, to contract, and 
thus produces what may be regarded as one of the most striking phenomena 
in nature.” 
The Habits of the Blue-Fish. — In the “Proceedings of the (American) 
Essex Institute ” we find the report of a paper, read by Captain H. E. Atwood, 
upon the change which has taken place in the habits of the blue-fish : — 
“ This fish, which many years ago was very abundant, and held in high 
estimation by the aborigines of our country, wholly disappeared from our 
coast in 1764, and not a specimen was seen on the coast, so far as Captain 
Atwood knew, for fifty years. In 1847 they teturned to the north of Cape 
Cod in great abundance, and have since been taken in large quantities in 
weirs and nets, and by the hook, near the shore. Now they avoid the shore, 
and, during the last year or two, have kept in the Bay, where it is difficult 
to capture them, as they seldom take the hook, though, until recently, they 
were most voracious and game fish.” 
The Anatomy of the Pulmonifera has been carefully investigated by Herr 
Leydig, of Tubingen, whose memoir appeared in Siebold and Kblli'ker’s 
Zeitschrift, and has been abstracted in the last number of the Microscopical 
Journal. The first part of this paper refers principally to the nervous 
system and organs of the senses, and minute histology of the nerves. Of the 
ear in these animals, the author observes that his investigations upon Arion, 
Limax, and Helix, give the following general results : — The capsule m all has 
the form of a shortly-stalked vesicle. The short stalk is only rendered per- 
ceptible by great care in the preparation. The short stalk serves to form a 
connection with the brain, and does not lead at all to the exterior of the 
head, so that consequently, when the parts under consideration are not 
altered through pressure or elsewise, the capsule appears, sharply defined hi 
all its remaining circumference, with a free border. The rest of the paper is 
devoted to the consideration of the admission of water hito 'the body, and 
