126 



ENTOZOA. 



Atcarisver- 



according to the sex ; the males rarely equal 

 two lines in length ; the females attain to five 

 lines (*fig. 73.) They are proportionally slen- 

 der, white, and highly elastic. The 

 Fig. 73. head is obtuse, and presents, ac- 

 \tt cording to the repeated observa- 

 tions of the experienced Rudolphi, 



- the three valvular papillae charac- 

 | v H teristic of the genus Ascaris ; but 

 11 I # other Helminthologists, who have 

 M 19 failed in detecting this organization, 



refer the species to the genus 

 Oxyuris. Besides the papillae the 

 head presents a lateral, semi-obo- 

 vate membrane on each side, the 

 broader end being anterior. The 

 body soon begins to grow smaller, 

 and gradually diminishes to a su- 

 bulate straight extremity in the 

 female. In the male the posterior 

 extremity is thicker, and is spirally 

 inflected and terminates obtusely ; 

 the head is narrower than in the 

 female. 



In the following tabular arrange- 

 ment of the internal parasites of 

 the Human body, they are disposed 

 3 classes to which they appear 



^Natural res P ect i ve ty to belong according to 

 size of their organization. 



female.) 



ENTOZOA HOMINIS. 



Classis PSYCHODIARIA, Bory St. Vincent. 



1. Acephalocystis endogena, cui locus 



Hepar, cavum Abdominis, &c. 



2. Echinococcus Hominis, Hepar, Lien, 



Omentum. 

 Classis POLYGASTRICA, Ehrenberg. 



3. Animalcula Echinococci, Hepar, &c. 



in Echinococco abdita.* 

 Classis PROTELMINTHA. 



4. Cercaria Seminis, Semen virile. 



5. Trichina spiralis, Musculi voluntarii. 

 Classis STERELMINTHA. 



6. Cysticercus cellulosee, Musculi, Cere- 



brum, Oculus. 



7. Tffnia Solium, Intestina tenuia. 



8. Bothriocepalus latus, Intestina tenuia. 



9. Polystoma Pinguicola, Ovaria. 



10. Distoma hepaticum, Vesica fellea. 

 Classis CGELELMINTHA. 



11. Filaria Medinensis, Contextus cellu- 



losus. 



12. Filaria oculi, Cavum Oculi. 



13. Filaria bronchialis, Glandulae bron- 



chiales. 



14. Tricocephalus dispar, Ccecum, Intes- 



tina crassa. 



15. Spiroptera hominis, Vesica urinaria. 



16. Strongylus gigas, Ren. 



17. Ascaris lumbricoides, Intestina tenuia. 



18. Ascaris vermicularis, Intestinum rec- 



tum. 



ANATOMY OF THE ENTOZOA. 

 Tegumentary System. There are few spe- 



* These may be considered rather as the Para- 

 sites of the Echinococcus than of the human sub- 

 ject. 



cies of the Sterelmintha in which a distinct 

 external tegumentary covering can be demon- 

 strated. In the Cystic, Cestoid, and most of 

 the Trematode worms, the parenchymatous 

 substance of the body is simply condensed at 

 the surface into a smooth and polished corium 

 of a whitish colour, without any development 

 of pigmental or cuticular layers. The various 

 wrinkles and irregularities, which the super- 

 ficies of these Entozoa frequently presents, 

 result from the action of the contractile tissue 

 of the corium : this substance, in the larger 

 Tcenitf, begins to assume a fibrous disposition, 

 and tears most readily in the longitudinal di- 

 rection ; it can be more distinctly demonstrated 

 as a muscular structure in the larger species 

 of Trematoda. By maceration in warm water 

 the rugae of the integument disappear; the 

 smooth external surface, so well adapted to 

 glide over the irregularities of a mucous mem- 

 brane, is then distinctly demonstrated; and, 

 when magnified, an infinite number of minute 

 pores, variously disposed, are seen perforating 

 the whole surface, especially in the Acantho- 

 cephalous worms. It is these pores which, in 

 the dead worm at least, allow a ready passage 

 to the surrounding fluid into the interstices of 

 the parenchyma, where it sometimes accumu- 

 lates so as to swell out the body to three or 

 four times its previous bulk ; and it may be 

 readily supposed, therefore, that the skin here 

 performs some share in the nutrient functions, 

 by absorbing a proportion of the mucous or 

 serous secretions in which the Entozoa are 

 habitually bathed. 



In the Acanthocephala the skin, which is 

 but little extensible and friable, is united to 

 the subjacent muscular fibres by means of a 

 whitish spongy tissue which adheres to it most 

 strongly opposite the dorsal and ventral longi- 

 tudinal lines or canals. As, however, the skin 

 is with difficulty changed by maceration, while 

 the parts which it surrounds soon go into 

 putrefaction, it can thus be easily separated 

 and demonstrated as a distinct substance. It 

 presents no definite fibrous structure under the 

 microscope, and tears with equal facility in 

 every direction. 



In a large Trematode worm, the Distoma 

 clavatum, Rud., which infests the intestines 

 of the Albicore and Bonito, the body is pro- 

 tected by a crisp sub-diaphanous cuticle, re- 

 sembling in its structure and properties that of 

 the Echinorhynchus. 



A similar covering may be demonstrated 

 very readily in the genus Linguatula, among 

 the Calelmintha, and can be separated, but 

 with more difficulty, from the subjacent mus- 

 cles in the Ascarides. In the great Round- 

 worm (Ascaris lumbricoides) the integu- 

 ment is smooth and unctuous, is more exten- 

 sible in the longitudinal than the transverse 

 directions, tears with an unequal rupture like 

 a thin layer of transparent horn, and preserves 

 its transparency in solutions of corrosive sub- 

 limate, alum, and in alcohol. In this species, 

 in which the digestive canal is completely de- 

 veloped, it is worthy of remark that the mi- 



croscope does 

 cuticle, as in 



not demonstrate pores in the 

 the external covering of the 



