1826.] On the Habits and Food of the Stickleback. 173 



we have A = 2 cos. ^-wtt. VB =0 .-.b + c =^0, or 6 = 

 — c. But, when & = — c, equation 21 gives d = -^ .'. — C 

 ~ ad = 0; that is B = ; so that here also A and B vanish 



iTo le continued.) 



I*. «, — ^ J 



simultaneously.* 



Article IV. 

 On the Habits and Food of the Stickleback.^ 



In volume 3 of the Journal of Science, p. 74, Mr. Rarnage, of 

 Aberdeen, has given an account of a Stickleback, which was 

 taken alive with a leech " fully as large as the stickleback 

 itself" in its intestines. The leech "in a few minutes" was 

 protruded by the anal opening, and crawled on Mr. Ramage's 

 hand ; but " the stickleback died almost immediately after 

 giving birth to the strange offspring, and the leech survived it 

 only about twelve hours." The appearance and motion of the 

 leech, it is added, " corresponded in every respect with those of 

 the common leech, excepting that the colour was entirely- 

 white." The theory oifered to account for this fact is, " that 

 the leech was lodged in the small gut, and most probably had 

 been swallowed by the stickleback for food when of a small size, 

 and had grown to its present dimensions in the stickleback's 

 belly, after having been swallowed." The leech and the stickle- 

 back were transmitted to the Museum of the Royal Society of 

 Edinburgh. 



Upon this detail it may be remarked, that the circumstance 

 of a stickleback swallowing a leech is no imcommon one, for 

 young leeches seem to be the favourite food of the three-spined 

 stickleback, Gasterosteus acideatus, Lin. My boys had several 

 sticklebacks alive for some months during the last summer, and 

 fed them at first with earth-worms, maggots, and occasionally 

 the small house fly, which, however, did not seem to be relished. 

 Afterwards, at my suggestion, young leeches were brought from 

 the ditch, in which the sticklebacks were caught, as being more 

 likely with the larvse of aquatic insects, to form part of their 

 natural supply, than the food which was submitted to their 



* The fallacy of Mr. Herapath's attempt to prove fc = ^ n to be admissible, lies in 

 his erroneous assumption of the " mutual independence " of the numerator and denomi- 



(6 + cY 



nator in the value of </ in this case. Even in tlie form • which he em- 



ij « (1 + COS. tt) 



ploys, the very condition of simultaneous evanescence marks tlieir dependence on each 

 other. For b + c = o, gives b' + c* = — 2 6 c .-. (fi + c)^ = 2 6 c - 2 A c at the 

 same time that the denominator becomes 2 o — 2 a ; which conducts to the same result 

 av I have given, 

 •f Edinburgh Journal of Science. 



