XXI. On the anatomy and physiology of the nematoids, parasitic and free; with observations on their zoological position and affinities to the echinoderms

Abstract

Although the parasitic Nematoids have been so long known and frequently submitted to anatomical examination, it is somewhat surprising that, even up to within quite a recent period, nothing was certainly known with regard to the arrangement in them of the nervous system, or as to whether they possessed any modification of the organs of circulation. The existence of both these systems has been asserted and denied over and over again by successive observers, and conflicting statements in this particular field of research have been so rife, that a well-known writer*, recently alluding to this subject, even goes so far as to state that the many discrepancies in the accounts given by leading Helminthologists of Nematoid anatomy “ tend to throw great doubt upon the general value of histological observations among the Helminths.” Although far from sharing in this opinion, I must admit that the tangled network of opposing statements is sufficiently disheartening.