Royal Microscopical Society. 55 



IV. — The Anatomy of the Bound-worm. 

 (Ascaris lumhricoides, Linn.) 



By B. T. LowNE, M.E.C.S. Eng. 



(Bead before the IIoyal Microscopical Society, Jan. 11, 1871.) 



Plates LXXV. and LXXVI. 



The anatomy of the Nematoida still remains in the greatest obscu- 

 rity, although Cloquet, Otto, Meisner, Schneider, Dr. Bastian, and 

 others, have contributed largely to the literature of the subject. 

 Numerous contradictions are found in their -v^orks, and much that 

 is unsatisfactory remains to be cleared up. 



About four months ago I "was fortunate enough to obtain fifty 

 or sixty large round-worms from a patient, who was the host of 

 nearly two hundred of these parasites. I thought this was a fa- 

 vourable opportunity to endeavour to clear up the more important 

 points in the anatomy of the Nematoid worms. The result of my 

 investigation has been most satisfactory to myself; and although I 

 differ in my conclusions from all previous writers, I have not hesi- 

 tated to pubhsh the results of my inquiry, as, if I am right, my 

 observations throw an entirely new hght upon the anatomy of the 

 Nematoids, and establish their place in the animal kingdom in a 

 most satisfactory manner. 



The Ascaris lumhricoides resembles an earth-worm at first 

 sight. The female varies from ten to sixteen inches, and the male 

 from five to eight inches in length. The extremities are tapered ; 

 the anterior extremity being more so. The alimentary canal runs 

 straight through the animal, the mouth and anus being situated at 

 the extremities. There is a distinct space between the body walls 

 and the alimentary canal, — the body cavity, — filled with a pink 

 serum-like fluid, in which the organs of generation lie. This fluid 

 keeps the external walls tense, and escapes with a gush when they 

 are ruptured. The duct of the female generative organs opens on the 

 ventral surface, at the junction of the anterior and middle thirds of 

 the body : that of the male has its orifice very near the posterior 

 extremity. A pair of curved spicules, retracted when at rest, con- 

 stitute the armature of the male generative aperture, one being 

 placed on either side of the opening. 



The body wall consists of the integument and of a thick layer 

 of longitudinal muscles beneath it. 



The integument exhibits two diverse layers, an external chiti- 

 nous and transparent, and an internal cellular portion. The external 

 layer is indistinctly segmented, exhibiting many hundred annuh. 

 This layer is apparently structureless, but may be split up into 

 numerous layers, a fact first pointed out by Czermack. It presents 

 no trace of cellular origin, and I am inclined to look upon it in the 



