1022 OP GENERATION. 



de Verde Islands) are accustomed to provide a wet-nurse in cases of emergency, 

 in the person of any woman who has once borne a child and is still within the 

 age of child-bearing, by continued fomentation of the mammse with a decoction 

 of the leaves of ihejatropha curcas, and by suction of the nipple. The most 

 curious fact, however, is that even Men should occasionally be able to perform 

 the duties of nurses, and should afford an adequate supply of infantile nutri- 

 ment. Several cases of this kind are upon record j 1 but one of the most recent 

 and authentic is that given by Dr. Dunglison. 3 " Professor Hall, of the Uni- 

 versity of Maryland, exhibited to his Obstetrical class, in the year 1837, a colored 

 man, fifty-five years of age, who had large, soft, well-formed mammae, rather 

 more conical than those of the female, and projecting fully seven inches from 

 the chest ; with perfect and large nipples. The glandular structure seemed to 

 the touch to be exactly like that of the female. This man had officiated as wet- 

 nurse, for several years, in the family of his mistress ; and he represented that 

 the secretion of milk was induced by applying the children intrusted to his 

 care to the breasts during the night. When the milk was no longer required, 

 great difficulty was experienced in arresting the secretion. His genital organs 

 were fully developed." Corresponding facts are also recorded of the male of 

 several of the lower animals. 



1023. The secretion of Milk consists of Water holding in solution Sugar, 

 various Saline ingredients, and the peculiar albuminous substance termed Casein 

 and having Oleaginous particles suspended in it. The constitution of this fluid 

 is made evident by the ordinary processes to which it is subjected in domestic 

 economy. If it be allowed to stand for some time, exposed to the air, a large 

 part of the oleaginous globules come to the surface, being of less specific 

 gravity than the fluid through which they are diffused. At the same time, there 

 is reason to believe that they undergo a change, which will be presently de- 

 scribed. The cream thus formed does not, however, consist of oily particles 

 alone ; but includes a considerable amount of casein, with the sugar and salts of 

 the milk. These are further separated by the continued agitation of the cream ; 

 which, by rupturing the envelops of the oil-globules, separates it into butter, 

 formed by their aggregation, and buttermilk, containing the casein, sugar, &c. 

 A considerable quantity of casein, however, is entangled with the oleaginous 

 matter, and this has a tendency to decompose so as to render the butter rancid ; 

 it may be separated by keeping the butter melted at the temperature of 180, 

 when the casein will fall to the bottom, leaving the butter pure, and much less 

 liable to change. The milk, after the cream has been removed, still contains 

 the greatest part of its casein and sugar. If it be kept long enough, a spon- 

 taneous change takes place in its composition ; the sugar is converted in to lactic 

 acid, and this coagulates the casein, precipitating it in small flakes. The same 

 precipitation may be accomplished at any time by the addition of an acid ; all 

 the acids, however, which act upon albumen, do not precipitate casein, as will 

 presently be pointed out in detail ; the most effectual is that contained in the 

 dried stomach of a calf, known as rennet. The whey left after the curd has 

 been separated contains a large proportion of the saccharine and saline matter 



1 See the case described by the Bishop of Cork, in the "Philosophical Transactions," 

 vol. xli. p. 813; one mentioned by Captain Franklin ("Narrative of a Journey to the 

 Polar Sea," p. 157) ; and one which fell under the notice of the celebrated traveller Hum- 

 boldt (" Personal Narrative," vol. iii. p. 58). 



2 "Human Physiology," 7th edit. vol. ii. p. 514. Dr. Dunglison also mentions that in 

 the winter of 1849-50, an athletic man, twenty-two years of age, presented himself at the 

 Jefferson Medical College at Philadelphia, whose left mamma, without any assignable cause, 

 became greatly developed, and secreted milk copiously. [Reported in "Philada. Medical 

 Examiner," Aug. 1850. ED.] It may be added that a lactescent fluid, apparently pre- 

 senting the characters of true milk, may frequently be expressed from the mammary 

 glands of infants. (See "Dublin Medical Press," April 17, 1850.) 



