TUBIFEX RIVULORUM. 15 



obtained seemed to be such as I had noticed, at the time of 

 gathering, lying in considerable numbers prone on the surface of 

 the mud, instead of being, as usual, buried therein, and present- 

 ing only the orifice ; and secondly, that, with one exception, they 

 were either devoid of their proper tenants, or else occupied by an 

 intruder in the shape of a " figure-of-eight," or blood-worm, as they 

 are familiarly called — the larva of Chironomus plumosiis. The 

 tubes thus found are flaccid, totally devoid of rigidity, yet having 

 sufficient coherence to render it difficult to understand how, on 

 the many occasions in which I have failed to find them in my 

 collecting-bottle all trace of them should have been destroyed 

 in the act of removal.^ The worms appear to be confined to very 

 narrow limits as to depth ; they are frequently covered with the 

 merest film of water, and never (so far as my observation extends) 

 is the red blush which indicates their presence found at a greater 

 depth than two or three inches. On this account I placed them 

 on reaching home, in a saucer, with about half-an-inch of water to 

 cover them, and have kept them in this condition for three or four 

 wTeks. I have never seen any attempt on their part to recon- 

 struct their tubes. They lay their eggs, however, plentifully at this 

 season of the year (February) ; and these are contained in capsules, 

 holding from one or two to six or eight. The capsules, which are 

 nearly white and about the size of a pin's head, begin to strew the 

 surface of the mud in the saucer in the course of a day or two. 

 After the lapse of some days, however, the worms do not thrive, 

 numbers of them being found in a fragmentary condition ; but 

 whether this is the result of a suicidal tendency, owing to unna- 

 tural conditions, or is the initial stage of the process of repro- 

 duction by fission, which is stated by many authors to occur, I am 

 unable at present to say. From the abundant deposition of eggs, 

 it is evident that numbers of them must have completed the 

 usual cycle of existence, and their decease on that account might 

 be expected \ but though the fragments appear lethargic and 

 unhealthy, and the vascular system has in many cases lost 

 its colour, yet vitality is evidently not extinguished ; and what is 

 more, the wound frequently seems to be healed by the formation 

 over it of a new skin. I have not as yet, however, seen anything 

 Hke the formation of a new head or tail.f 



Various authors have at different times described the ana- 

 tomy and habits of Tubifex. The most important treatises, how- 



* Since writing the above, I have had reason to doubt whether the tubes above 

 described are the work of the annelid or of the larva. If the latter, I have never 

 seen as yet a trace of the tubes from which the worm takes it name. 



t It should be noted that Dr. Williams strenuously denies reproduction by 

 fission in the annelida. See Report of the British Association for 1851, p. 247. 



