FIELD AND FOREST. I41 



tremity is unattached for one-hundreth of an inch or less, then penetrat- 

 ing the septum, it enters the succeeding chamber where the tube is bent 

 upon itself several times, and where it suddenly dilates into a kind of 

 pouch, which also turns upon itself once; it suddenly contracts, dips 

 down in front of the ventral rows of setae, to all appearance passing 

 between the setigerous muscles and opens externally — where ? That it 

 does open externally there is no doubt. The precise point is a 

 mystery only equalled by the difficulty in guessing why the internal 

 opening should be in one chamber and the exit in another. I have 

 several times seen on the abdominal surface in front of the ventral setse, 

 toward the median line and somewhat inclined to the course of the 

 circular fibres, narrow orifices to which I think I have traced the tubes, 

 but that I have seen the true openings I am not prepared to affirm. 

 Seeking them is much like searching for the well-known needle in the 

 familiar hay stack, with a success generally quite as remarkable. To 

 find each succeeding one demands a search as severe, prolonged and 

 aggravating as the first. 



Their use? It is one of Nature's well kept secrets. To the earnest 

 questionings of the most learned naturalists she has returned no an- 

 swer. One has supposed them to be a respiratory svstem, and the 

 liquid moving within them by the aid of the cilia a respiratory fluid 

 obtained from the damp earth. It may be so; the blood vessels wind 

 about and cover them with a net-work of tortuous loops, where the 

 blood might be purified by the oxygen suspended in the liquid. 

 Another suggests that they may be part of the generative system, utero- 

 ovaria, in which the eggs may undergo a part of their development. 

 Still another, and this is the most generally accepted opinion, that 

 their function is to supply the skin with the mucus that so abundantly 

 covers it and is so copious when the surface is irritated. In nearly 

 every instance I have found the dilatations filled with a thick, almost 

 sebaceous matter, and in every examination of the living canals this 

 matter has at once stopped the ciliary motion when forced into the 

 tubes. In none of my victims could it have been possible for any 

 fluid to have passed without first forcing out this semi-solid accumula- 

 tion. However, their use is all conjecture. It is known only to Him 

 who made them. 



An account of the life-history, the physiology and micro-anatomy 



