76 ILLINOIS BIOLOGICAL MONOGRAPHS [196 



EXPLANATION OF PLATES 



Plate I consists of photomicrographs made from slides. The other 

 figures were drawn either from slides by means of a camera lucida or from 

 photographs by means of a copying lens. Magnifications were obtained 

 in case of drawings by the projection of the stage micrometer scale on 

 the paper and in case of photographs by projecting the stage micrometer 

 scale on the focussing screen. 



The original thesis deposited in the library of the University of Illinois 

 contains 656 figures, of which all but twelve are photomicrographs. Those 

 photographs illustrate many points in the description that could not be 

 shown in the drawings. 



The author is indebted to the University of Illinois for special services 

 from an artist of the university to draw a number of the figures. He is 

 likewise indebted to the Zoological Division of the Bureau of Animal 

 Industry at Washington, D. C. for permitting the artist of the division 

 to draw a large number of the figures. 



The abbreviations I 4, I 7, and I 8, as used in the descriptions of 

 figures, are the serial numbers of the infection experiments and are de- 

 scribed in the section on parasitism in Gordius robustus. 



