A Description of the Thread-worm, Filaria immitis. 159 



details ; enough facts were obtained, however, to demonstrate that 

 the worm was a filaria, and that the name hitherto appKed — 

 spirojytera — was misplaced, a point subsequently corroborated by 

 Dr. Cobbold in a letter to the 'Lancet,' March 15th, 1873, conse- 

 quent on my paper, and in which he mentioned that the term 

 Filaria immitis had been given to the worm in Germany. Since 

 this time, through the kindness of Dr. D. Macdonald, F.K.S., 

 Assistant Professor of Naval Hygiene, Army Medical School, I 

 have received the heart and one lung taken from a dog at Yoko- 

 hama, Japan, by Staff- Surgeon H. Hadlow, K.N., containing nume- 

 rous and comparatively recent specimens of the blood- worm — male, 

 female, and free young ; and the results of the examination of these 

 are embodied in the present paper. I have applied the name Filaria 

 immitis to these on the assumption that they are similar to those 

 fouud in Germany and referred to by Dr. Cobbold, and I propose 

 in this communication to detail the anatomy of the worms, and 

 subsequently to append a few remarks on the h^matozoa in general 

 — animal and human. 



Mature Female Worm. — Body long, thread-like, cylindrical 

 (Plate XXX., Fig. 3), averaging 11 inches in length, but varying 

 from 8 to 13 inches, with a body diameter of 2V inch in the centre, 

 ■So inch at the head, and y^ inch at the tail; head blunt and 

 rounded ; tail bluntish, yet tapering towards a point ; both gradually 

 merging into the central maximum body thickness ; colour, milk- 

 white, opaque, but rendered translucent by immersion in glycerine. 

 Worm coiled uj), yet easily straightened out ; tail straight ; animal 

 markedly resembling a piece of white twine, with an occasionally 

 annulated condition of the centre or tail end, and especially in those 

 fully distended with ova and embryos. With an ordinary hand-lens, 

 while holding the worm up to the light, a differentiation of its 

 structural components could be made, into the parietes, and internal 

 viscera. The latter were made up of two dark tubes — one smaller 

 (alimentary canal), traceable from the head throughout the entire 

 body length, with the exception of the immediate tail end; the 

 other larger (generative canal), apparently commencing about half 

 an inch from the head, and terminating about an inch and a half 

 from the tail, the latter interval being filled in by a convolution of 

 small tubes. By the aid of glycerine and higher magnifying powers, 

 further details were brought out, as follows : — The parietes were 

 composed of cutaneous and muscular strata. The former consisted 

 of a cerium externally covered by imbricated longitudinal layers of 

 a beautifully delicate minute epidermis, much resembling that on 

 ophidians ; the latter was made up of three layers in the following 

 relation from the corium inwards : two oblique intersecting each 

 other at an acute angle, a longitudinal, a circular, all varying in 

 the degree of development in different situations. The combined 



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