158 ANIMAL-SENTIENT FORCES. [i. 



machines which have to accomplish sexual congress, namely, 

 the organs of generation, since it stimulates them to their ap- 

 propriate functions (178-179), and in particular is developed 

 fully the satisfaction of the instinct, namely, sexual congress. 

 Hence we understand why in this instinct the organs of gene- 

 ration fall into the same state as in coitus (217), that state 

 being induced according to the laws of the sentient actions of 

 sensational instincts. These incomplete movements becoming 

 complete in the satisfaction of this instinct, in accordance with 

 the designs of nature, other phenomena having reference to the 

 propagation of the species, result, as impregnation, conception, 

 the formation and nutrition of the embryo, and, lastly, its birth, 

 an account of which may be found in works on the Physiology 

 of the Special Mechanism of Animal Bodies. (Haller's ' Physio- 

 logy,' 28th Division.) 



The Instinct to give Suck, 



290. The instinct to suckle is one of the most remarkable 

 of the instincts of parent animals for their offspring. It arises 

 by the prevision of nature in the maternal animal, which gives 

 suck even at the period when a young creature is about to be 

 born, and in consequence of an unpleasant external sensation 

 from the distension of the mammse with milk, which is the 

 sensational stimulus of the instinct. Everything that induces 

 this sensation in the mammae, excites the instinct to give suck ; 

 so that bitches, whose mammse swell about the time when they 

 ought to whelp, have the instinct fully developed, although not 

 in pup at the time, and willingly allow a strange dog to suckle 

 them. The instinct itself is a strong desire to attain to the 

 sensation contrary to that of painful distension, or in other 

 words, a desire to empty the mammse, which is the design of 

 nature, as well as the object of the animal, although it is other- 

 wise ignorant to what end the suckiug of its mammae subserves. 

 The painful sensational stimulus changes the vital movements 

 contra-naturally (271, 276, iv), as is proved by the great un- 

 easiness, and by the milk fever ; and, as a foreseeing of a future 

 agreeable sensation of suckling, manifests its sentient actions 

 in such a way, that it stimulates the mammae to similar func- 

 tions, and partly develops them according to the laws of the 



