PLATES 



EXPLANATION OF PLATES 



The drawings were made with the aid of a camera lucida, using a Zeiss 2-mm. 

 apochromatic immersion objective, N. A. 1.30, and a Spencer compensating 

 ocular 20 X which produced a magnification of 2633. The illumination consisted 

 of light from a 100-watt frosted-globe Mazda concentrated-filament lamp passed 

 through a daylight glass or a common cobalt-blue glass filter, and an Abbe con- 

 denser. The observer was shaded from the light in front of him and from the 

 sides by a black-cloth screen. 



In reproduction plates 1 to 8 have been reduced one-third, and plate 9 three- 

 fourths, giving a final magnification of 1755 and 1316, respectively. 



Figures 1 to 20 represent complexes of class I; figures 21 and 23, complexes of 

 class II. 



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