EXPLANATION OF THE PLATES. 361 



ad, \ slender canal, which by opening into the mouth and 

 then extending and contracting, unites with the stomach and 

 intestinal tube.— X, A triangular mass, or rather stomach.— 

 ef, The intestinal tube terminating in gh.—i, A small aper- 

 ture to give passage to the excrements and organs of genera- 

 tion. — d I, A small white canal, which, passing under the tri- 

 angular mass Xf and intestinal tube fg, reaches to the end 

 of the tail k I. Here the genital organs of the male are prob- 

 ably inclosed, which communicate externally through the ori- 

 fice i — / m, Very fine end of the tail, perforated by very mi- 

 nute bodies. 



Fig. IX. A female ascaris vermicularis, magnified by the micros- 

 cope (no. 4, tube A,)— a, Eminences at the superior extrem<- 

 ity of the head, hardly visible in a dead ascaris.—?; c. Two 

 oval eminences like jaws, as in the male, separated by the 

 mouth a. — a d, A canal, which conveys the food into the stom- 

 ach e, communicating with the intestinal tube from /to g, be- 

 yond which we see tlie transparent tube gh, Avhich is proba- 

 bly an appendix of the intestinal tube. — i, A considerable ap- 

 pendix to the tail, .which is characteristic of the females. — fr, 

 The vagina, through which the female deposits her young. — . 

 I, The place where tlie small canal, forming the vagina t, is 

 given off. The dark bodies from f to g are fetuses, which 

 can be in great part expelled from the vagina fc, by simple 

 pressure. 



Fig. X. A portion of the membrane of a female ascaris vermicu- 

 laris, compressed and seen with the fetuses through the micro- 

 scope (no. Ijtube A.) 



Fig. XI. The fetus of an ascaris vermicularis, enlarged by the 

 microscope (no. l,tube A.) 



PLATE FIFTH. 



Fig. I. The entire body of a lumbricoides, so situated as to ex- 

 hibit its four lateral lines. — a, The trilobed head. — b, The pos- 

 terior extremity, or tail. — cdef, The four lateral lines. 



Fig. II. Tail of tlie lumbricoides.— fr, A tubercle, under which 

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