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TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



four inches apart, running the whole length. At one end 

 of the board was screwed a 5 x 4 Planex Reflex camera. 

 I removed the panel carrying the lens, and temporarily 

 fixed on a 10-inch wooden extension for the lower 

 magnifications, and a longer extension made with wire 

 and brown paper for the higher magnifications. These 

 extensions ran along the rails as the camera was racked 

 out. A 2-inch block of wood, also running on the rails, 



Fig. 5. — Four stages in the early development of the Plaice before 

 hatching. From photomicrographs by Edwin Thompson. 



carried a cell in which was the living larva in sea- water. 

 A second block of wood carried an 8-inch condenser. The 

 illumination was obtained from an acetylene bicycle 

 lamp. 



" The lens used for photographs 1, 2 and 3 was a Zeiss 

 micro-planar of 35 mm. focal length ; and for photographs 

 4 to 9 a 3i-inch Beck. The lenses were stopped down 



