CH. III.] SUCKLING. 159 



actions of sensational instincts (271-72, 277), as sentient 

 actions actually requisite to suckling, and resulting from the 

 completion of the instinct ; so that, for example, the milk fever, 

 whereby the milk is produced, supervenes, and the nipples are 

 erected (105, 247). The sentient actions of the instinct itself 

 consist in the effort of the animal-sentient forces to attain 

 these same imperfect movements (272), and through these, by 

 means of the connection of the physical, mechanical, and animal 

 forces of the organs adapted for suckling, the further operations 

 in the animal economy are attained, as the emptying of the 

 mammae, a more free circulation in them, the further quiet 

 secretion of good milk from the glands, and the prevention of 

 induration and impaction, all in accordance with the design of 

 nature in the instinct. {Vide Haller's 'Physiology,^ § 133.) 

 It is obvious from common experience, how this instinct is 

 adapted to another in the offspring, namely, the instinct to 

 suck; but inasmuch as this is only a particular form of the 

 instinct for food already treated of at length (281-82) it is 

 unnecessary to enter here into detail. 



291. It would be equally unnecessary (and perhaps wearying) 

 to go through the other instincts in detail, inasmuch as the 

 preceding explanations and principles are applicable to all. 

 We need only here state the general laws by which the 

 phenomena must be explained, which the sensational instincts 

 develop in the animal economy. Whether all these pheno- 

 mena be always true sentient actions from sentient instincts, 

 or always such in all animals, or whether they are in some 

 degree, or altogether, nerve-actions (183), as has been often 

 mentioned (266, 269, 285), all these questions must be left 

 undetermined, until we come to the Second Part of the work. 

 It is sufficient to state at present, that the phenomena of the 

 instincts, in so far as they are true sentient actions, can be ex- 

 plained on no other principles than those hitherto laid down. 

 Nevertheless, it will not be useless to prepare the reader for the 

 doctrines of the Second Part by a few general statements and 

 deductions. 



292. It is indubitably clear, from the nature of the instincts, 

 that the true sensational instincts, together with their sentient 

 actions, result naturally and necessarily from external im- 

 pressions, much in the same way as external sensations and 



