167] LIFE HISTORY OF GORDIUS AND PARAGORDIUS—MA 7 47 



host. The definite reaction toward the presence of water was again observ- 

 ed. On July 12 a male of Gryllus assimilis was found to have the anterior 

 end of a female of Paragordius varius protruding from the posterior end 

 when it was caught. The cricket was placed in a dry vial and the parasite 

 withdrew and remained in the host until the latter was placed in water 

 in the laboratory two hours later. In the water the parasite left the host 

 in less than five minutes. The emergence was witnessed by Dr. W. W. 

 Cort and Mr. A. C. Conger. Other similar cases were observed during the 

 summer. 



ORGANOGENY 



On account of the lack of material in the early stages little can be said 

 about the metamorphosis and derivation of tissues in this species. Only 

 two young specimens were obtained and they were mounted as totos 

 (Figs. 130, 131). 



Cuticula. Stages in its development in this species are even more 

 difficult to obtain than in Gordius robusius indicating that the cuticula 

 develops with extreme rapidity. 



Larval cuticula. It was in this species that the shedding of the 

 larval cuticula was first observed. Nevertheless, its presence is difficult 

 to demonstrate during the development of the adult cuticula. It is clearly 

 evident in younger stages and changes in size and thickness during develop- 

 ment just as does that of the previous species. But no homogeneous layer 

 appears under it before the beginning of the development of the adult 

 cuticula. Much later, when the fibrous cuticula has almost reached its 

 full development, a very thin, homogeneous layer appears under the larval 

 cuticula (Fig. 167) but is difficult to distinguish because it adheres closely 

 and has nearly the same density and staining reactions. The larval cuticula 

 later separates from this layer (Fig. ^163) and comes off in large sheets, 

 being retained longest at the ends. Adult specimens removed from their 

 hosts frequently show these pieces of the larval cuticula trailing from the 

 two ends. When such sheets of larval cuticula are mounted and stained 

 they show a perfectly homogeneous structure. 



Adult cuticula. The development of the adult cuticula commences with 

 the formation of a rather indefinite granular layer under the larval cuticula, 

 but almost simultaneously there appears under this a lighter layer which 

 is the beginning of the fibrous cuticula. The granular layer is the rudiment 

 of the homogeneous or non-fibrous cuticula and areolar structures of 

 the adult. Fibrous cuticula and areolar structures develop simultaneously 

 (Figs. 161, 169). The stains employed failed to bring out any structures 

 in the fibrous cuticula during its development. The hypoderm cells 

 often give off conical projections into the developing cuticula and the 

 apices of the cones can sometimes be seen to extend to the granular 

 layer (Figs. 166, 167). At the points where the apices reach the granular 



