Organic Acids on Cotton and Flax Fibres. 113 



The facts contained in the preceding paper are interesting, 

 as indicating the extent to which less powerful, though still 

 sufficiently characteristic actions may be overlooked. Hitherto 

 we have gone upon the supposition that the organic acids are 

 entirely without action upon vegetable fibres, and constant use 

 is made of them by the calico-printers in the production of 

 their colours. My observations, however, sufficiently show 

 that they cannot be used for this purpose without injury; and 

 should serve as a warning to avoid their use, and to replace 

 them as far as possible by neutral salts. 



In conclusion, I may mention, as somewhat allied to the 

 subject of this paper, that I have succeeded in making use of 

 the difference of the action of weak animal acids on vegetable 

 and animal fibres, as a means of detecting the admixture of cot- 

 ton and flax with wool. The latter resists an acid which en- 

 tirely destroys the former. This fact has acquired consider- 

 able practical importance from the extent to which mixed fa- 

 brics have been introduced of late years. 



On a Hermaphrodite and Fissiparous Species of Tubicolar 

 Annelid. By Thomas A. Huxley, F.R.S., Lecturer on 

 General Natural History in the Government School of 

 Mines. 



In the course of a series of dredging operations, in which I 

 have lately been engaged, upon the shores of Caermarthen Bay, 

 in the neighbourhood of Tenby, I took, upon one occasion and 

 in one locality (in about six fathoms water, near Proud Giltar), 

 the Annelid which is the subject of the present communica- 

 tion. It is questionable, however, whether the animal is so 

 rare as I might have been led to suppose from this solitary 

 instance of its occurrence within my own knowledge — for I had 

 afterwards the opportunity of seeing masses of its calcareous 

 habitation considerably larger than that which I took my- 

 self, in the celebrated collection of the late Mr Lyons of 

 Tenby. 



The Vermidom (as one might conveniently term the habi- 

 tations of tubicolar annelids in general) of this annelid is 



VOL. I. NO. i. — JAN. 1855. h 



