48 ILLINOIS BIOLOGICAL MONOGRAPHS [168 



layer the latter becomes thickened and in it are developed hyaline 

 bodies, usually two at each point (Figs. 104, 161, 169). These hyaline 

 bodies later become oval in outline and give the cuticula its areo- 

 lated appearance (Fig. 160). The homogeneous cuticula, which always 

 remains more or less granular, is formed from the granular layer chiefly 

 over these bodies, but also between and under them. The connections 

 between the granular layer and the hypoderm remain as definite proto- 

 plasmic strands, coming to the surface usually between the oval bodies 

 (Figs. 1, 160, 164). At intervals heavier protoplasmic strands pierce 

 the fibrous cuticula, and over them the granular layer thickens to form 

 the short cuticular tubercles or bristles which are found especially in 

 two ventral rows, but also sparingly scattered over the rest of the body 

 (Figs. 140, 164). Where the heavier strands pass thru the cuticula the 

 fibers remain separated to form a cross (Fig. 1). At the sides of the male 

 cloacal aperture the bristles in the two ventral rows are very much elonga- 

 ted. Anteriad from that point they gradually shorten, posteriad they 

 remain high to the bases of the prongs and then become shorter and are 

 scattered over the inner ventral surfaces of the prongs (Fig. 133). The 

 oval bodies are absent on these surfaces. 



The outer surface of the homogeneous or non-fibrous cuticula is usually 

 hyaline in appearance, while the granules remain evident in a lower layer 

 which indefinitely grades into the hyaline layer, and at places may be 

 absent or at others may reach the surface. The bristles are composed 

 chiefly of the hyaline substance, but usually show at the base a cone of the 

 granular material. Since the granular substance stains deeply it has been 

 impossible to trace the protoplasmic strands farther than to the bases of 

 the bristles. 



Fibers do not appear in the cuticula until it has reached nearly 

 its full diameter. They are wound spirally around the body in two 

 directions so that they cross each other forming antero-posterior angles of 

 about 175 degrees and lateral angles of about 65 degrees (Fig. 1). Since 

 the fibers are all of the same size and the layers alternate regularly, cross 

 sections of the cuticula do not present the appearance of stratification so 

 obvious in the cuticula of Gordius robustus unless the sections are made 

 nearly parallel to one set of fibres. The number of layers of fibers is vari- 

 able, but seldom exceeds 24. Montgomery reports only 11, but his figures 

 show that he made his counts on sections parallel to one series, and counted 

 only alternate layers. Over the white surface at the anterior end the fibers 

 become more closely packed and tend to form a homogeneous mass. 



The color appears in the manner described for Gordius robustus and 

 reaches its full intensity before the parasite leaves its host. On June 30 a 

 female was removed from the host when it was still incompletely colored. 

 The dark ring and the dorsal and ventral bands were clearly outlined. 



