building can be watched ; but in order to see it to perfection the water 

 must be kept in rapid circulation by means of a paddle-wheel, as 

 described in the introduction, or some other mechanical means. After 

 floating along for some minutes in the current the larva manages to 

 get a foot-hold on the side or bottom of the dish, usually in that 

 part where the motion of the water is most violent, and sets to work 

 at once to build itself a new protecting home. That they greatly 

 appreciate a strong current is shown by the fact that quite a number 

 of the larvae in my permanent dishes always take up their position 

 on the edge of the paddle itself, where the motion is so strong that 

 their nets are often broken. 



The first thing the larva does is to gather a number of particles 

 of mud together and form them into a short strap or band passing 

 across the middle of the body and fixed to the dish on each side. 

 Using this band as a starting point the larva sets about building a 

 simple straight tube closely applied to the dish and open at both ends ; 

 at first the band is merely broadened so as to cover more of the 

 body, but soon it is shortened as well until length and breadth change 

 places and a real tube is formed. It is interesting to watch the 

 methodical way in which material is collected. Anchored, as it were, 

 to the strap by its anal feet, it rapidly sweeps through an angle of 

 about 60, touching the surface here and there with its mouth as it 

 passes ; then firmly grasping a particle by means of the labral armature 

 and the anterior appendages, it powerfully contracts its body, thus 

 drawing the particle towards the centre of operations ; but not only 

 does the above mentioned particle move, but all those touched during 

 the sweeping movement follow in its wake, having been united together 

 by silk threads or mucus during the first action. In this way abundance 

 of material is collected and the building of the case proceeds rapidly. 

 When all the larger grains have been removed in the neighbourhood 

 of one end of the growing tube, the larva turns round in its case and 

 repeats the same action at the other end. After having removed all 

 the larger objects it is curious to watch how carefully it gathers up 

 every speck, using the epipharynx like a rake, until a perfectly clear 

 space is left for some distance all round the primitive tube. 



