A Description of the Thread-worm, Filaria immitis. 165 



of a globular, papilla-like body, rather less than xoVo^ inch in thick- 

 ness, not projecting beyond the epidermis, by their attached end 

 continuous with the horse-shoe duct [m), and opening into it by a 

 smaller duct traversing the gland in its long diameter. The sub- 

 stance of these glandular bodies was identical in character with the 

 material occupying the horse-shoe duct into which they discharged 

 themselves, and no external aperture was detected. Their connec- 

 tion with the duct opening into the seminal tube evidently associates 

 them with the generative function, and their secretion mingled with 

 the spermatic fluid would find its way by the vas deferens to the 

 groove of the spiculum and so into the uterus of the female. 



Hence, then, from these anatomical details, we may sum up 

 these mature worms as having a filiform musculo-cutaneous cylin- 

 drical envelope, containing an alimentary, generative, and water 

 vascular system, the sexes distinct and the reproductive organs 

 largely predominating, mouth circular and papillary, intromittant 

 organ of the male sub-caudal, genital orifice of the female situated 

 on the anterior end of the worm within 2 inches of the oral orifice, 

 alimentary canal csecal. 



Free Young Worm composing the Brood. — These were micro- 

 scopic, free within the vascular canals of the host equally with the 

 parent worms, and so numerous that a piece of blood clot the size 

 of a pea, taken from the left ventricle of the dog's heart and 

 broken up in a teaspoonful of glycerine, gave twelve specimens to 

 two drops of the fluid from a pipette. The young worm was of 

 filiform shape, identical in relative thickness of parts of body with 

 the mature worms, head rounded, tail pointed, average length 

 gV inch, thickness toVo inch, proportion of breadth to length 1 to 47, 

 proportion of tail to total length 1 to 8, body structure translucent 

 with delicacy of texture or granular from fatty degeneration or fat 

 particles within the alimentary canal and then removed by the 

 addition of liquor potassae. Following the contour of the external 

 surface was an inner line which mapped ofi" a transparent parietes, 

 corresponding to the "tube charnu" of the mature worm and 

 merging into the general translucency of the tail end of the young 

 animal. On the addition of magenta colouring the textures be- 

 came more easily distinguished the one from the other, and un- 

 doubted transverse striae were noted along the concave margin of 

 the curled body of the worm, as well as often faintly elsewhere. 

 By the colour staining of the body, especially after the dispersion 

 of the fat-granules by the potash solution, a light -refracting 

 inversion of the cuticle over the head, indicating the mouth, was 

 perceptible, and from it an alimentary canal was feebly, though in- 

 dubitably, marked out, while one or two darker lines were trace- 

 able along the length of the body of the worm, stopping short of 

 the tail. The dead animal was easily broken across, when the dis- 



