196 



THE AMEEICAN 



thick dermis. Tliis is composed of layers of 

 fibres which pursue a spiral direction around 

 the body of the worm, alternating- or crossing 

 in the successive layers. "Within the thick skin 

 of the worm there is a thicker muscular layer, 

 composed of longitudinal fibres. 



The Gordius is a wonderfully prolific animal. 

 The mode of impregnation I have not observed. 

 In the European Gordius aquaticus, Dr. Meiss- 

 ner observed that the tail end of the male wound 

 spirally around that of the female, and by its 

 forked extremity grasped that of the latter, 

 while the genital pores were closely applied 

 togetlier. 



The Variable Gordius and the Loug-lobed 

 Gordius extrude their eggs in a long, narrow 

 white cord, from between the lobes of the tail, 

 as represented in Figure 120, h. I observed a 

 Variable Gordius, 9 inches in length by 2-5ths 

 of a line in thickness, commence laying eggs, 

 aud continue the process very slowly and 

 gradually during two weeks. They were ex- 

 truded in a delicate cylindrical cord, resembling 

 a thread of sewing cotton. At first it broke ofi", 

 as extruded, in pieces about a foot in length, 

 but, towards the end of the process, the cord 

 appeared to be less tenacious, and broke ofi' in 

 pieces a few inches, and even a few lines, in 

 length. The pieces in the aggregate measured 

 91 inches ; the thickness of the cord was about 

 the 1-lOth of a line. The eggs are very minute, 

 and in the cord were compressed together so as 

 to be polyhedral. In a transverse section of the 

 cord I counted about 70 eggs, and in the length 

 of l-40th of an inch 26 eggs, which by calcula- 

 tion gives 6,624,800 as the whole number of eggs 

 in the cord. The eggs when isolated assume an 

 oval shape, and measui-e about the l-750th of an 

 inch long by the 1-lOOOth of an inch broad. 



The development of the young from the egg 

 is readily observed from day to day ; and it takes 

 about a month before the process is completed. 

 The globular mass of yolk in the centre of the 

 egg undergoes segmentation, and increases in 

 bulk until it is finally resolved into an oval mass 

 of granules occupying the gi-eater part of the 

 interior of the egg. Gradually the mass assumes 

 the appearance of a worm doubled upon itself, 

 as seen in the magnified view (Fig. 120, o). In 

 about four weeks the Gordius reaches maturity, 

 and escapes from the egg totally different in 

 appearance from the parent (Fig. 121, 2> q r). 



The newly developed Gordius is about the 

 l-450th of an inch long. The body is constricted 

 just posterior to the middle, so as to appear 

 divided into two portions, reminding one of the 

 two divisions of the body in spiders. The an- 



terior thicker portion of the body is cylindrical, 

 distinctly annulated, and contains a complex 

 apparatus which the animal is capable of pro- 

 truding and withdrawing. The posterior part of 

 the body is cylindrical, annulated, and rounded 

 at the extremity, which is furnished with a pair 

 of minute hooks. The interior exhibits a faintly 

 granular structure, including two large, clear, 

 globular bodies. 



[Fig. 121.] 



,^, r n 



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, refiection 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 centre of the head (Fig. 121, p). These 

 continue to project and diverge more and more, 

 and then become reflected. As they turn back- 

 ward the ends of the second circle of hooks are 

 observed protruding in the same manner, and 

 then follows the style (Fig. 121, 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. 121, r).. In a reverse order the dif- 

 ferent parts of the apparatus are retracted, to be 

 again proti-uded in the manner described. 



The newly developed Gordii, under my ob- 

 servation, 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 larvas of May-flies {Ephemeridm) , 

 and Caddice-flies (Phryganeidce.) , he observed 

 that they entered these insects, and thus com- 

 menced their parasitic life. The worms were 

 observed to penetrate the delicate membrane at 

 the joints of the legs of the insects, and gradu- 

 ally to advance among the muscles and other 

 organs throughout the body. In some of the 

 insects as many as forty of the young Gordii 



