Prof. C. Semper on the Anatomy o/" Comatula. 203 



2nd ed. Miiller further on (I. c. pp. 58, 59) describes the ovaries 

 as lying in the pinnules completely isolated from each other, 

 and compares this situation to that of the analogous organs in 

 the proglottides of the Cestoda. 



The cord discovered by Miiller (I. c. pi. iv. fig. 11, pi. 

 v. f. 16) between the two canals of the arm — which, more- 

 over, is wanting in the drawing of a section of the arm of 

 Comatula europaia (I. c. pi. iv. f. 12) — is indeed present; it is 

 not, however, the nerve-system, but belongs to the parts of 

 generation. This is proved by sections of the arm of a new 

 Comatula from the Philippines,, which I shall subsequently 

 describe ; the sections were made on arms carefully decalcified. 

 The pinnules, as is well known, arise with a tolerably sharp 

 curve towards the arm. At the period of sexual maturity the 

 ovaries prolong themselves in the same direction into the soft 

 portions of the arm before uniting with each other through the 

 cord (Midler's nervous cord) which runs along the middle line. 

 In transverse sections, therefore, made close behind the inser- 

 tion of a pinnule, the prolongations of the ovaries which are 

 situated in the hinder part of the arm, under the groove of the 

 tentacle, must be met with, and, in a favourable case, also the 

 cords connecting them with the central cord. Such sections 

 are in fact obtained with tolerable facility. In the annexed 

 woodcut (fig. 1), on the left the pinnule is not met with; but on 

 the right it is, though only partially. In the proper body-parts 

 of the arm, under the tentacle-canal c.t (from which the late- 

 ral vessels depart for the tentacle) a cord r, cut through some- 

 what obliquely, is seen in the middle line : this is Miiller's 

 nerve of the arm (see fig. 2). To the right of it is situated a 

 portion of the right ovary, ov, with developed ova mostly on 



baur quotes from my Monograph of the Hohthurice in his ' Lehrbuch ;' 

 his readers are not informed of the existence of such a work, but only that 

 I published some observations on Holothuria in my ' Reisen im Archipel 

 der Philippinen.' I myself can bear the disadvantage thence arising ; but 

 it is not so easy for others to do so, because they are led into error by his 

 authority. Recently a Privatdocent at Graz has -written a special memoir 

 on the histology of the Holothuria, without the slightest suspicion that he 

 could have found all his supposed novelties already in my booh. More- 

 over I cannot suppress the conjecture that Gegenbaur himself has not 

 carefully read my work ; otherwise he would hardly have granted a 

 place in his own to manifest errors. For it is not true that (as he 

 says, p. 343 of the 2nd edition of his 'Grundziige') "neither the structure 

 nor the function of the Cuvierian organs are known." The former is 

 better explained by me than almost any other organ by others ; and the 

 negative result of my investigation, that they were certainly not glands, 

 is much more positive than Gegenbaur's absolutely arbitrary assumption 

 that they are " probably excretory organs *' (I. c. p. 320). 



