436 Chronicles of Science. [July 



will now grant him the time to study, so that when he again finds 

 himself afloat he may be able to do that service in zoological science 

 which his perseverance and artistic skill would ensure. 



Physiology. 



The Moving Force of a Singh Cilium. — An interesting experi- 

 ment has been recently made by Dr. Jeffreys Wyman, of Cambridge, 

 Mass., and repeated by Dr. Bowditch, of Boston, now in Professor 

 Ludwig's laboratory at Leipzig, which suggests to us the above 

 heading. If the ciliated membrane from the palate and fauces of 

 the common frog be carefully removed and stretched on a perfectly 

 smooth plate whilst quite fresh and moist, and on this surface a 

 weight be placed, its surface being carefully covered with a piece of 

 fresh peritoneum of the frog to prevent the contact of dead matter 

 with the cilia, it will be found that the weight is slowly moved 

 along by the force of the cilia, a weight of as much as four grammes 

 being actually transported in this way — slowly but perceptibly. 

 Dr. Bowditch has varied the experiment by cutting off the head of 

 a frog and inserting a glass tube into the mouth, so that the ciliated 

 surface may work on the rod, and he has actually succeeded in causing 

 the head to move along the rod when in a horizontal position or but 

 very slightly inclined against the direction of movement, simply by 

 the ciliary power. It would be interesting to know the mechanical 

 equivalent of a single cilium ; that is to say, what fraction of a horse- 

 power, for instance, a cilium power may be. 



The Movements of Wings in Flight. — It is to Dr. J. Bell Petti- 

 grew, T.K.S., of Edinburgh, that the credit is due of first advancing 

 the view that during flight the movement of wings is such as to 

 describe a figure of eight if progression of the whole Jbody be hin- 

 dered. In an elaborate investigation into the mechanism of flight 

 in various animals, insects, birds and bats, he demonstrated that the 

 structure was such as to provide for and necessitate this form of 

 movement ; in fact, the wing should act as a reciprocating screw. 

 Whilst acknowledging that Dr. Pettigrew has the merit of first 

 giving this account of the movements of flight, Dr. Marey, of Paris, 

 the illustrious physiologist, who has so successfully applied the 

 graphic method to the study of the circulation and of muscular 

 contraction, has demonstrated the truth of Dr. Pettigrew's inference 

 from structure by actual experiment. An insect's wing being gilded 

 and a strong beam of light used, its movement could be followed 

 by the eye ; also by allowing it to brush against a cylinder covered 

 with lamp-black, the figure of its movement was obtained. Dr. 

 Marey is now investigating by most ingenious methods the flight of 

 birds — with a view to determine exactly what is the effective part 



