Mr. A, Macalister on Secreting Organs in Nematoidea. 45 



VI. — On the Presence of certain Secreting Organs in Nema- 

 toidea. By Alexander Macalister, F.R.C.S.I., Demon- 

 strator of Anatomy, Royal College of Surgeons, Ireland. 



The existence of special secreting organs in the Nematoid 

 Entozoa is by no means a discovery of very modern date ; for 

 several of the earlier helminthologists have described various 

 parts of the animals in this class as subservient to the function 

 of secretion. Of late, however, our knowledge of these struc- 

 tures has been much extended, mainly through the increasing 

 perfection of the microscope, which has thrown light upon all 

 branches of invertebrate anatomy, and has shown us greater 

 complexities of structure in those creatures which had previously 

 been regarded as of simpler organization. 



Four series of these glandular organs have been already de- 

 scribed in different Nematoids ; and I think that the apparatus 

 which I am about to notice is entitled to rank as a fifth kind of 

 secreting organ, separate in function from any of those at pre- 

 sent known. Those already recognized are — (1) The salivary 

 caeca described by Owen in Gnathostoma spinigera, consisting of 

 four small blind tubes communicating with the mouth : similar 

 organs Siebold has noticed in Strongylus striatus; and although 

 some have doubted the function assigned to them (Bagge, in 

 Appendix to 'Thesis de Evolutione Strongijli auricidaris/ &c.), 

 yet I think we are justified in adopting Owen^s view as being 

 correct. (2) Cloquet, in his work on the anatomy of Ascaris 

 lumbi'icoides, describes the thickened parietes of the oesophagus 

 as being glandular, probably secreting a fluid to assist in the 

 assimilation of the food. (3) There are in many species intes- 

 tinal cseca with which Owen associates an hepatic function. 

 Mehlis, in the 'Isis' for 1831, figures and mentions several of 

 these ; and Siebold, in his ' Anatomy of the Invertebrata,^ refers 

 to their occurrence in several species, especially in Ascaris he- 

 terura, A. semiteres, A. depressa, A. angulata, A. ensicaudata, 

 A. mucronata, and A. osculata. Leidy, in the ' Smithsonian 

 Contributions,^ pt. 5. p. 49, pi. 7, figures and describes one of 

 these organs in Thelastomum appendiculatum ; and Diesing no- 

 tices another in a species of Ascaris infesting the Dugong. 

 The 4th and last-described gland (leaving out of account the 

 secreting parts of the reproductive apparatus) is the curious 

 tubular organ described by Siebold (Bagge, loc, cit. supra) in 

 the Stro7igylus auricularis and Ascaris brevicaudata, A. acuminata, 

 A. paucipara, and A. dactyluris, which opens near the middle of 

 the body on the ventral aspect, and which in the last-named 

 species I have on several occasions traced with considerable 

 facility. 



