140 



ENTOZOA. 



are separated in the greater part of their extent 

 by a septum : see Jig. 84, J', g, which shows 

 them in transverse section. They contain a 

 prodigious quantity of ova, and adhere by 

 their outer surfaces very firmly to the muscular 

 parietes of the body. 



The dorsal ovary opens into the ventral one 

 by an oblique valvular aperture about an inch 

 distant from the extremity of the proboscis, 

 anterior to which the common cavity extends 

 forwards between the lateral lemnisci, and 

 terminates by a conical canal (i, fig. 83), which 

 is attached to the posterior portion of the pro- 

 boscis. The two ovaries terminate in a dif- 

 ferent manner posteriorly, the dorsal one end- 

 ing in a cul-de-sac, the ventral becoming 

 continued in a slender oviduct (K), which 

 opens by an extremely minute pore at the 

 caudal extremity of the body (I). The tissue 

 of the ovaries is remarkable for its trans- 

 parency and apparent delicacy, but it pos- 

 sesses a moderate degree of resistance. 



The generative organs in the Nematoidea 

 are upon the whole more simple than in the 

 Acanthocephala. 



The testis in each of the genera is a single 

 tube, but differs in its mode and place of ter- 

 mination, and the modifications of the intro- 

 mittent part of the male apparatus have 

 afforded good generic characters. 



Genitals musculum, spiculum simplex, is the 

 phrase employed by Rudolphi in the formula 

 of the genus Filaria, and this appears to be 

 founded on an observation made on the Filaria 

 papillosa, in which he once saw a slender spicu- 

 lum projecting from near the apex of the tail. 

 According to the recent observations of Dr. 

 Leblond,* the male-duct in the Filaria papil- 



Fig. 94. 



Penii of Ascaris lumbricoides. 



* ' Qnclqucs Matcriaux pour srrvir a I'Histoirc 

 do Filaircs ct Suongles, 8vo. 1'aiis, 1836." 



lusa terminates at the anterior extremity of 

 the body close to the mouth. From this 

 aperture the slender duct, after a slight con- 

 tortion, is continued straight down the body to 

 a dilated elongated sac, which represents the 

 testis. 



In the Ascaris lumbricoides the penis (a, fig. 

 94) projects from the anterior part of the anus 

 in the form of a slender, conical, slightly curved 

 process, at the extremity of which a minute 

 pore may be observed with the aid of the micro- 

 scope. The base of the penis (6) communicates 

 with a seminal reservoir, and is attached to 

 several muscular fibres, destined for its re- 

 traction and protrusion : the reservoir is about 

 an inch in length, and gradually enlarges as it 

 advances forwards : the testis or seminal tube 

 is continued from the middle of the anterior 

 truncated extremity of the reservoir; it pre- 

 sents the form of a long, slender, cylindrical, 

 whitish-coloured tube, extends to the anterior 

 third of the body, forming numerous convo- 

 lutions and loops about the intestine, and its 

 attenuated extremity adheres intimately to the 

 nutrient vessels of the dorsal region of the 

 body. The total length of the seminiferous 

 tube in an ordinary sized Ascaris lumbricoides 

 is frorn two feet and a half to three feet. Its 

 contents, when examined with a high micro- 

 scopic power, consist of a transparent viscous 

 fluid, in which float an innumerable quantity 

 of round white globules, much smaller than 

 the ova in the corresponding tubes of the 

 female. In the genus Trichocephalus the fila- 

 mentary testis is convoluted around the intes- 

 tine in the enlarged posterior part of the body. 

 The intromittent organ in the Trichocepliulus 

 dispur is inclosed in a distinct sheath, which 

 is everted together with the penis, and then 

 presents the form of an elongated cone (c, 

 fig. 69), adhering by its apex to the enlarged 

 anal extremity of the body, and having the 

 simple filiform spiculum or penis (d,Jig. 69) 

 projecting from the middle of its base. 



In the Strongylus gigas the bursa or sheath 

 of the penis terminates the posterior extremity 

 of the body, and is a cutaneous production, 

 of a round, enlarged, truncated form, with the 

 spiculum projecting from its centre, as at B, 

 Jig. 71. In other species of Strongylus, as in 

 the Strongylus injle.rus, the bursa penis is bifid, 

 and in the Strongylus urmatus it is divided 

 into four lobes : the obvious functions of these 

 appendages, as of the lateral alffiform cuta- 

 neous productions which characterize the P/iy- 

 saloptertc and Spiropterx, is to embrace the 

 vulva of the female, and ensure an effective 

 intromission and impregnation of the ova. 



In the genus Cucullanus, and in most of the 

 smaller species of Ascaris, the intromittent 

 organ consists of a double spiculum. 



This is also the case in the Syngnmus tra- 

 chcalis, the parasitic worm before alluded to as 

 infesting the trachea of the common fowl, and 

 occasioning the disease termed the ' Gapes.' 

 In this species the male individual appears as 

 a branch from the body of the female. The 

 testis begins near the middle of the (Esophagus 

 by a slender blind extremity, and winds round 



