TIlHKK-Sl'INKl) S'l'I(KI,KIiA(K. 



(;.').") 



The tuliul;ir cliniiiher is cHJiistrurtcd. and the I'onii .-iiid 

 diiniliilil\ 'it' tlic wiiole nest iittaiiied, liy the Siicklc- 

 baek swiiiiiniii^i;' slciwly oyvv the; parts already in po- 

 sition, and at the same time gluing them tugetiier 

 and ceinenting them. Evers distinetly observed how 

 tiie liuiitler, when he had added new la\ers, sliunk his 

 tins, raised liis head, lient his hi)d\' np\\:ir(ls. and slid 

 iiis bellv over the struetiire, emittinL:' at the same time 

 a drop of a viscid snhstanee. \\hieh eonld he <dear]y 

 distinunished in the water, and the eH'ecIs of which 

 mi'dit immediatch he [>erceived in the no\v cemented 



building-materials'. At times he si k the building 



and then pressed it together again; at times he kept 

 swimming ovei- it. With his tins, «hicli he ke]it in 

 continual and rapid motion, he |)roduced a current, 

 and thus washed away from the nest the pieces that 

 jvere too light and the loose stalks, which he then 

 took up again and tried to fit in more durabh. It 

 took about tour hours to procure the \arious building- 

 materials; but at the expiration of this time tlie out- 

 lines of the nest were readw Its completion, the re- 

 moval of the parts that are too light, the arrangement 

 of the separate stalks, the plaiting of their ends, and the 

 addition- of the sand to weigh them down, require several 

 da\s. While the Sticd^lebaek is building his nest, he 

 thinks ()id\ of his work and endeavours mereh to pro- 

 vide against any interruption in its progress or hind- 

 rance to its completion. He labours indefatigably and 

 watches with suspicion everv creature that approaches 

 the nest with or without evil intentions, whether it lie 

 another Stickleback, a newt, a water-beetle, or a lar\a. 

 A water-.scorpion {Xejja) in one of Evers' aquaria was 

 seized bv the cautious builder thirty times or more, and 

 carried in his mouth over to the opposite .side of the 

 aquarium. 



The size of the nest varies prettv considerabh-, de- 

 pending both on its situation and on the materials of 

 which it is composed. As a rule it seems to be of the 

 size of one's tist. It is generally ellipsoidal and entirely 

 closed above, but furnished at the ends with an en- 

 trance and an exit. At first oidy the entrance is 

 visible, but subse(|uentlv, exactlv opposite it, \ve <lis- 

 cover the exit. \Mien the Stickleback has finished his 



building-cjperations, he endeavours to attract a female 

 to the nest. \VAi!i(iN(;'rox sa^■s that a comjdeted nest 

 excites the attention of the female; but C'h.ste asserts 

 that the male sallies forth to guide her thither, and 

 that he ushers her into the nest with a shower of ca- 

 resses. The last statement, howe\ci', is also accepted by 

 WAi{i.'iN(;roN. The inale distincth' sliows his delight at 

 the arrival of the fennde, swims round hei' in all di- 

 rections, enters the nest, sweeps it out, returns in a 

 moment, and tries to dl'i^•e the female in by thrusting 

 at her from behind with his snout. If she will not 

 obe\' of lu'r own accord, he also employs his s])ines, 

 or at least his caudal tin, to overcome her reluc- 

 tance; but in case of need another female is fetched. 

 If tlie male succeeds in ]iei-suading a female to enter 

 the nest, she la\s a few eggs within it, according to 

 ( '(isiE only two or three, and then l)ores a hole through 

 the vvall of the nest on the side opposite to the eii- 

 ti'ance, and departs. The second opening in the nest 

 does not exist until it is formed in this manner. The 

 current that now flows through the openings, is of 

 beneiit to the eggs. i)n the following day the male 

 sets out again in (piest of a new female, whom he com- 

 pels bv kindness or force to \;i\ eggs, and repeats this 

 process until a sufficient number of ova is procured. 

 During or inunediately after the la\ing of the spawn 

 he enters the nest, rubs his side against that of the fe- 

 male, and then glides over the eggs in order to ferti- 

 lize them. 



From this hour his zeal and watchfulness are re- 

 doubled. He has to guard and defend the eggs against 

 every aggressor. Ever)- Stickleback that approaches is 

 furiousl}' attacked and put to flight, whether it be a 

 male or a female, for both are equally dangerous ene- 

 mies of the eggs, and the latter is perhaps even more 

 greedy of the ova or the new-hatched h'j than the 

 former. Until the \oung have emerged from the eggs, 

 the male shows his cai'e in other ways as well. With 

 his mouth he repairs every damage to the nest, and 

 often stations himself in front of or within the cham- 

 ber, keeping his pectoral fins in vibration and thus 

 renewing the water in tlie nest, as though he knew 

 that the eggs require fresh oxvgen. 



" MuBiiis (.\'atiire. vol. XXXIX, No. 998, Dec. \A. 1888, p. 108) saw the male Stickleback keep spinning round the nest new threads, 

 which originated from tlie urinary bladder. The eheniical reactions showed that these threads consist of mucin, which is secreted, however, 

 not by the urinary bladder, but by the kidneys. The section of a kidney, treated with osfnic acid and coloured with hematoxylin, showed 

 that only a few of the cells lining the tubtili nrini/eri partake in t\\c development of the mucin, while most of them do not undergo any 

 chauge of this description. After the end of the spawningseasou. no mucinous cells can be found in (lie kidneys, which are now less tumid. 



