330 REPORT UNITED STATES ENTOMOLOGICAL COMMISSION. 



of minute hooks. The interior exhibits a faintly granular structure, including two 

 large, clear, globular bodies. 



The young Gordius appears not to be able to swim about, but lies at the bottom of 

 the vessel containing it, slowly progressing through the alternate protrusion, reflection, 

 and retraction of the oral apparatus, and occasionally swinging the hinder part of the 

 body from side to side. 



The oral apparatus consists of a collar, with two circles of hooks, six in each, and a 

 proboscis-like style. In the movements of this apparatus, the ends of six hooks are 

 seen to protrude from the center of the head (Fig. 65, 2^)' These continue to project 

 and diverge more and more, and then become reflected. As they turn backward, the 

 ends of the second circle of hooks are observed protruding in the same manner, and then 

 follows the style (Fig. 65, q). When the latter is fully protruded, the first circle of 

 hooks is seen at the margin of a collar deeply reflected at the side of the body, while 

 the second circle of hooks is reflected from the margin of the head (Fig. 65, r). In a 

 reverse order the diflferent parts of the apparatus are retracted, to be again protruded 

 in the manner described. 



The newly developed Gordii, under my observation, continued to live about a week 

 more, and then gradually died. 



Dr. Meissner was successful in following the history of the animal a step further. 

 Having placed in the same vessel with the young Gordii a number of larvae of May- 

 flies (Ejjhemeridw) and Caddice-flies (Fhryganeidw), he observed that they entered these 

 insects, and thus commenced their parasitic life. The worms were observed to pene- 

 trate the delicate membrane at the joints of the legs of the insects, and gradually to 

 advance among the muscles and other organs throughout the body. In some of the 

 insects as many as forty of the young Gordii had penetrated. They afterwards became 

 quiescent, doubled on themselves, and encysted, so as to resemble their former condi- 

 tion just before emerging from the egg. In this state they recall to mind the similar 

 encysted Trichinse in the muscles of man and the hog. 



Dr. Meissner observed no further change in the Gordii, while contained in the insect 

 larvae, nor did he detect them after feeding some of the latter to Water-beetles. 



Thus from the young Gordius, which has escaped from the egg and entered upon its 

 parasitic life in the interior of insect larvae, to the parent Gordius, as it is commonly 

 observed, either as a parasite or living in the water, the circle of the animal's history 

 is broken and unknown. 



Perhaps the young Gordii remain quiescent in the May and Caddice-flies until these 

 undergo their last transformation in the air, when they may be seized and devoured 

 by Ground-beetles, which are ever lurking beneath stones and other objects in the 

 vicinity of water on the lookout for prey. Once eaten by the beetles, like Trichinae 

 swallowed by the hog, the Gordii may then undergo transformation, and assume the 

 form of the parent Gordius, which is said especially to infest the Ground-beetles. 



M. A. Yillot has, more recently ,^^ added to our knowledge of the life- 

 history of these curious creatures, as will be seen by the following ac- 

 count of his discoveries, condensed by Mr. Packard : 



The eggs (Fig. 66, a) are laid in long chains ; they are white, and excessively numer- 

 ous. The yolk undergoes total segmentation (Fig. 66, 6). At the close of this period, 

 when the yolk is surrounded by a layer of cells, the germ elongates at what is destined 

 to be the head-end, this layer pushes in, forming a cavity, and in this state it is called 

 a ''gastrula" (Fig. 66, c). By this time the embryo becomes pear-shaped (Fig. 66, d) ; 

 then it elongates. Subsequently the internal organs of digestion are formed, together 

 with three sets of stifi", spine-like appendages to the head, while the body is divided 

 by cross-lines into segments. The head lies retracted within the body (Fig. 66, e). 



In hatching, it iDierces the egg-membrane by the aid of its cephalic armature and 



8^ Monocraphie dea Dragonneaux (Genre Gordius Dujarclin), par A. "Villot. (Archives de Zoologie 

 exp6rimentale et gen6rale, tome 3, Nos. 1, 2, 1874, Paris.) 



