324 Mr. W. C. Minor on Natural and Artificial Section 



work ' von Wiirmern des siissen und salzigen Wassers/ Kopen- 

 hagen, 1771, largely devoted to that subject, shows that he failed 

 only where the imperfect means at his command led him astray. 

 The multiplication by artificial section had been observed before 

 that, both in the Naids and other animals, and had awakened a 

 good deal of general interest ; but the multiplication by sponta- 

 neous fission seems to have been very nearly, if not wholly dis- 

 regarded at that time. Nor has its occurrence in the freshwater 

 worms received, since then, the investigation that it seems to de- 

 mand ; for, with the exception of a discussion by Schultze and 

 Leuckart upon some of the particulars, and the significance of 

 this phenomenon in relation to budding, some ten years ago, 

 and a sweeping denial of its occurrence, or, at least, of its vital 

 and systematic nature, by Dr.Williams, about the same time, no 

 one, so far as I am aware, has published any extended observa- 

 tions upon the fissiparity of the freshwater Naids since the time 

 of Miiller*. And yet the statements of Dr. Williams^ in regard 

 to both artificial and spontaneous fission, are such as to suggest 

 at once the importance of a re-examination of the whole subject; 

 while the great interest given to this question by the remarkable 

 speculations of Steenstrup, together with the interesting varie- 

 ties of the phenomenon as observed in the marine worms by 

 Quatrefages, Edwards, Frey and Leuckart, and others, seem to 

 demand a more complete knowledge than we as yet possess of 

 its occurrence in the freshwater group. 



I may here remark that the European species chiefly studied 

 hithei'to, Stylaria proboscidea, has not come under my observa- 

 tion, nor am I aware that it has been found in America. Four 

 species of Naids common in this vicinity, Stylaria {Pristina) 

 longiseta, Nais rivulosa, and Dero limosa, found in fresh water, 

 and a marine Enchytrceus [E. triventralopectinatus) have been the 

 principal subjects of my investigation. In regard to the first of 

 these, it may be questioned whether our species is identical with 

 that described by Ehrenberg (' Symbolse Physicse ') as Pristina 

 longiseta ; for his description is too brief to be of specific value. 

 As, however, the characters given by D'Udekem in his "Nouvelle 

 Classification des Annelides Setigeres Abranches " (Memoires de 

 FAcad. Royale de Belgique/ 1859, t. xxxi.) apply equally to the 

 American species, I am compelled to regard it as the samef. 



* Gruithuisen remarks, in his " Anatomie der geziingelten Naide" (Nov. 

 Act. Nat. Cur. t. xi. p. 243), only that it is uncommon to find a Naid with- 

 out buds of the second generation, and refers to Miiller for the details of 

 their formation. Since writing this, I have seen, in Leuckart's valuable 

 yearly report in the Archiv f. Naturgeschichte for 1861, a notice of 

 Claus's observations on fission in Chcetog aster, which, so far as there given, 

 I can confirm. 



t D'Udekem remarks : " Je n'ai pas adopte le genre Stylaria admis par 



