422 



VKKTEBKATA. 



tliU j'foiioiuv of the ii.-itinf ot" tlifsi- aiiiinuls, the cjrors of the female being taken to any desired 

 lo«-ality and j»la<-i-d in the water, ami strown with tlic milt of the males. 



At the season for deposit in;; the spawn, wiiicli varies with almost every genus, some species 

 repair to the gravellv shallows of rivers, and others to the sandy bays of the sea. This move- 

 ment is railed l.y (ishennen "t/olnf/ to hi/f" or '^ roadiixj ;"' other species resort to bunches of 

 weeds. The objeet of that remarkable instinct in fishes which induces many species, as the her- 

 rinirs, pilchards, mackerel, A'c., to perform Ioiil; miniations, is doubtless to secure proper places 

 in which to deposit tlu'ir spawn. The shad thus ascends our rivers in the spring, and the salmon 

 in lik»' manner not only i)asses up the streams, but often, with an astonishing perseverance and 

 vi'^or, shoots up cascades and waterfalls which might be supposed to present insuperable 

 obstacles. 



In many instances, when ready to deposit her spawn, a female is accompanied by two males, 

 one on each side — a provision of nature which seems intended to secure the impregnation of the 

 lariTcst (piantitv of ova; and beside, the range of the influence of the male fluid is enormously in- 

 creased by ditl'usion in water. The adhesive nature of the surface of each egg supplies the means 

 of attachment to any of the various substances near wliidi it may happen to be left; tlie time 

 required for the appearance of the young fish is very variable, depending upon the species, and the 

 season ami its temperature. The young fisli is first apparent as a line wound round the central 

 vitelline portion of the a^^'^, and ultimately escapes by rupturing the external capsule with its 

 tail. The spawiung appears to take place only once a year. Many fishes, liowever, are what is 

 called ovo-viviparous ; that is to say, the ova are retained within the oviduct until the complete 



evolution of the embryo. Tlie 

 mode in which the impregnation 

 of the ova is eft'ected in those cases 

 is not exactly known. Fishes ap- 



I pear always to select shallow water 

 ?j for the deposition of their ova ; but 



beyond this they do not genei'allv 



exhibit any care for their offspring. 



A few, however, form a sort of nest 



' for the protection of their eggs and 



, young ; and in some instances, the 



I I male remains as a guard over the 

 fiy until they have acquired suffi- 



-\ cient strength and agility to ven- 

 ?! turc forth into the world. The 

 little sticklebacks, common in 

 h ponds, furnish an interesting ex- 

 I ample of the exercise of this in- 

 stinct. Similar instances of care 

 for the 2)kice where the ova are de- 

 : posited are furnished by the Eu- 

 ii ropean river bull-head and the 

 S^- 2: lump-sucker. Instances of attach- 

 j-j ment between the parent fishes are 

 2;J also known among a few species. 

 j The nundjer of fishes in the va- 

 rious waters of the earth surpasses 

 all human conception. Every pond, 

 stream, river, and lake, as well as the ocean, covering three-fourtlis of the surface of our globe, 

 swarms with these creatures. Such are the provisions of nature to maintain and multiply 

 fishes, that streains which are dried up during the hot season are soon after supplied with abund- 

 ance of these creatures, ow-ing, no doubt, to the hatching of eggs wdiich have been deposited in 



:\ 





NEST OP STICKLEBACKS. 



