3638 Habits of the Water-snail and Stickleback 



kept four minnows and two small eels, and in the second the stickle- 

 backs which form the subject of this observation. In this the male 

 fish commenced gradually to deposit and accumulate his materials. I 

 will endeavour to give in detail the exact description of his proceed- 

 ings while I had the opportunity of watching him, avoiding as much 

 as possible the repetition of his operations ; for as each loose fibre or 

 small piece of material was brought singly to the chosen spot, the 

 same routine would be gone through over and over again. Now he 

 arrives with a large fibre in his mouth, deposits it, rearranges the 

 whole of the materials, already accumulated, with his mouth, remov- 

 ing one fibre to this place and another to that, and departs on his 

 search for more. Now he returns, carrying a small piece of gravel, 

 which is carefully placed on part of the fibres as it were to keep them 

 down ; he then draws himself slowly over the whole and is off again. 

 Now he brings another fibre, which he dibs in with his snout so as to 

 make it interlace with the others ; then he attempts to interlace in the 

 same way the fibrous rootlet of a Lemna which is growing above his 

 head, but which, the instant he thinks he has fastened and loosens his 

 hold of, rises again by its expanded lobe to the surface; this fibre ap- 

 pears to be well fitted for his purpose, for he repeats his attempts to 

 fix it among his gleanings over and over again. Now he is busy mak- 

 ing a circular hole in the middle of the accumulated materials with 

 his snout ; a piece of the fibre is next taken out from the mass, pro- 

 jected from his mouth, watched as it falls very slowly through the 

 water ; then, as it proves too light for his purpose, it is again seized, 

 carried to some distance, and projected away, and he is off to rear- 

 range the remainder, carefully tucking in the ends with his snout ; he 

 then draws himself slowly across the whole and is off again. Now he 

 catches a sight of the female fish, pursues her with great rapidity, and 

 seizes her by the tail and by the lateral spine, but she escapes his 

 grasp and conceals herself behind the rock-work. Again he conveys 

 more material to the nest, and the next journey is again laden with 

 another small piece of gravel ; the whole is then slightly shaken, then 

 compressed, and he is off again ; thus he conveys, without cessation, 

 decayed rootlets, gravel, sand, and whatever material he can find that 

 will answer his purpose. But I must observe that their specific gra- 

 vity is continually tested : thus, haying found what appears a suitable 

 fibre, it is carried a little way, then projected to a short distance from 

 his mouth and watched as it falls ; if it falls rapidly, it is again seized 

 and carried direct to the nest ; if more slowly, it is tried again in the 



