114 



THE HELMINTHE3. 



§109. 



tions, and which terminates in a short muscular rectum. The proper intes- 

 tine is of a brown, greenish, or dirty yellow color, which is due to its walls 

 being formed of compact cells filled with colored granules. The loose and 

 cellular walls, having very feeble peristaltic movements, are surrounded 

 externally by a kind of dense peritoneum, and lined internally by a very 

 fine epithelium.'^' In some species of Ascai-is, the intestine is lengthened 

 into a caecum at its junction with the oesophagus.''"' 



§ 109. 



There are observed, here and there, only traces of appendant organs of 

 the digestive canal. 



In many Trematodes, there are upon each side of the neck, two more or 

 less developed cords or canals, of a cellular aspect, and of a pale yellow 

 color by direct light. They pass towards the mouth, open perhaps into its 

 cavity, and have a function, probably, like that of salivary organsß^ In 

 many Nematodes, two or four caeca extend from the cephalic extremity 

 along the (.esophagus, and as they open distinctly into the oral cavity, it is, 

 therefore, the more probable that they should be regarded as salivary 

 organs.'-' The same signification should be given to the coecal appendage 

 found in many species of Ascaris, which extends from the constriction of" 

 the oesophagus to the beginning of the intestine.'''' 



Hepatic organs have been found nowhere but in the Nematodes; but it 

 may be that the granular cells in the thick walls of the intestinal canal, 

 take their place. 



5 This epithelium has sometimes special inequali- 

 ties, which, with Ascaris osculata, and spicu/ige- 

 ra, form a regular zig-zag series, resemljling the 

 valves of the intestinal mucous membrane of some 

 vertebrates. With Ascaris aiicta, they have the 

 form of long, sharp villosities. 



6 This caecal appendage, accompanied usually 

 ■with a constriction of the posterior end of the 

 oesophagus, was first observed by Mehlis (Isis. 

 1831, p. 91, Taf. II. fig. 16, 17, IS). It is found 

 with many Ascaris, but its length is very variable. 

 In Ascaris hetertirn, srmiteres, and ensicaudata, 



scarcely beyond the 

 ; w\dle in Ascaris depres- 



.1 iiiiirrnnrifa, it ri-;iclicÄ to 

 ,:vj\\<, aiul ill A^ruri.s- s/,i. 



I llic <lirrirs llrMTil.cl ilS 



plialic 



it is very short, :iim1 i 



oesophageal const li 



sa, aucta, angnlut 



the middle of thr i 



culigcra, osc)il(il< 



Filaria piscium, it extends nearly to tl 



extremity.* 



I These glandular-like organs are often very 

 distinct iu'tlie cercarian larvae of the Trematodes, 

 and in many adults of Mnnostomujn, and Disto- 

 Tniun ; see IViegmann''s Arch. 184:3, II. p. 322. 



a Mehlis (Isis, 1831, p. bl, Taf. II. fig. 6) has 

 observed with Utronsyliis annatus, an annular 

 vessel surrounding the mouth, which communi- 



cates with it directly, and also with two cords 

 accompanying the tesophagus. According to him, 

 there is also a similar disposition with Strongylus 

 hypostomiis, and tetracanthus. 



Similar appendages, analogous to salivary or- 

 gans, occur, according to Owen, in the new genus 

 Gnathosoma, as four caeca surrounding the oeso- 

 phagus, and opening into the mouth (JVieg- 

 maiin^s Arch. 18.38, I. p. 134). With Cheiracan- 

 thus, and Ancyracanthus, there are four similar 

 organs, and Diesing is certainly in error in 

 regarding them as analogous to the ambulacra! 

 vesicles of the EeliinodiTiiis (Ann. d. Wiener Mus. 

 II. Abth. 2, p. 224, 22<i, 22S, Taf. XVII. fig. 8, 9, 

 Taf. XVIII. fig. 3). I am disposed to regard as 

 salivary organs, also, tlie two long caeca which 

 pass from the mouth along the oesophagus of 

 Strongylus strialus. 



■'! I have discovered a similar oesophageal ap- 

 Ijeudage in a group of Ascaris known as Filaria 

 piscium (jyiegmaM^s Arch. 1838, I. p. 309) ; 

 such are, Ascaris mucronata, angulata, oscu- 

 lata, spiculigera, aucta, aciis, and labiata. It is 

 remarkable that with the exception o the last two, 

 all these have also a caecum upon the intestine. 



* [ § 108, note 0.] See, for the alimentary canal 

 of Ascaris infecta, Lcidy (A Flora and Fauna 

 within living animals, Smithsonian Coutrilj. V. Art. 

 2, p. 43, PI. VI. fig. 1-7). lie divides it into a 

 strongly muscular gizzaril, a cylindroid intestine 

 lined with hexahedral epithelium, and a pyriform 

 rectum. 



See also his description of that of Streptoso- 

 mum, Thelastomum, &c. (Ibid. p. 49). In The- 



last.nmnm njipendiculatum, there is thi.-! pecu- 

 liarity, that the intestine commences by a broad, 

 deeply sinuate, cordiform dilatation, which rapidly 

 narrows to a short, cylindroid portion, and then 

 sends off a long, capacious, gourd-form receptacle, 

 or diverticulum, and afterwards proceeds back- 

 wards to the rectum, and in its course, in the vi- 

 cinity of the generative aperture, performs a single 

 short convolution. — Ed. 



