October 11, 1901.] 



SCIENCE 



567 



The study of the origin of the fish groups 

 of Japan affords a fascinating index to its 

 multifarious problems. 



David Starr Jordan. 



Stanford University. 



Tiri: LABORATORY TEACHING OF PHYS- 

 IOLOGY* 



The student of physiolog}' should per- 

 form the classical experiments upon which 

 the science rests. The writer of these 

 papers has for several years endeavored to 

 place the laboratory teaching of physiology 

 within the reach of every school. To ac- 

 complish this it is necessary that apparatus 

 of precision be designed upon lines per- 

 mitting its manufacture in large quantities 

 at a small cost. The apparatus described 

 below is believed to show progress in this 

 direction. 



the box admits the rays from a lantern or 

 other source of light. This circular window 

 may be closed by a clear glass plate or by any 

 of the several diaphragms described below. 

 Two pins, one at the side and one below 

 the opening, are so placed that when the 

 diaphragm rests against them its aperture 

 will lie in the axis of the optical system. 

 The lenses and mirrors employed with the 

 box are mounted in square wooden blocks, 

 to protect them from injury. When the 

 side of the wooden block is placed against 

 the ' rabbit strip ' shown at the lower inside 

 angle of the box the center of the lens or 

 mirror mounted in the block will lie in the 

 optical axis. The rays of light entering the 

 box are made visible by the fumes of Japan- 

 ese incense, a small stick of which is lighted 

 and placed in a hole in a cork upon which 

 fits a tin cylinder shown in Fig. 1. 



Fig. 1. The optical lantern and artificial eye. 



I. THE artificial EYE. 



The artificial eye (shown in section in 

 Fig. 1, one fourth the actual size) consists 

 of a wooden box the top of which is closed 

 by laying upon it a piece of clear plate- 

 glass. A circular opening in the front of 



* Porter, W. T. : Boston Medical and Surgical Jour- 

 nal, Dec. 29, 1898. Philadelphia Medical Journal, 

 Sept. 1, 1900. ' An Introduction to Physiology, ' Cam- 

 bridge, 1900 and 1901. ' Experiments for Students in 

 the Harvard Medical School,' Second Series, Cam- 

 bridge, Jan., 1901. Third Series, Cambridge, May 

 1901. 



The optical lantern consists of a sixteen- 

 candle-power electric lamp, with small 

 spiral filament, mounted in a wooden box 

 pierced with holes which permit thorough 

 ventilation but do not allow the escape of 

 light to disturb the observer. The lantern 

 box is provided with a condensing lens and 

 two focusing lenses mounted in draw tubes 

 which may be easily removed. The slot 

 for the diaphragms is furnished with a stop 

 so placed that when the diaphragm is 

 shoved against it the aperture of the 



