622 



PHYSIOLOGY OF GONADS 



sens, 1950; Kalliala and Karvoncn, 1951; 

 Kalliala, Karvonen and Leppanen, 1952). 

 It was also shown that electrical stimulation 

 of the nerve paths to the posterior pituitary 

 resulted in milk ejection (Cross and Harris, 

 1950, 1952; Andersson, 1951a, b, c; Popo- 

 vich, 1958 », and that when lesions were 

 placed in these tracts the milk-ejection re- 

 flex was abolished (Cross and Harris, 1952) . 



Further evidence was adduced when it 

 was found that removal of the posterior 

 pituitary immediately abolished the milk- 

 ejection reflex in the lactating rat, and that 

 it was necessary to inject such animals sev- 

 eral times a day with oxytocin if their litters 

 were to be reared (Cowie, quoted by Folley, 

 1952b). Earlier workers had claimed that 

 the posterior lolie was not essential for lac- 

 tation (Smith, 1932; Houssay, 1935), but an 

 explanation of these discordant conclusions 

 was provided when it was shown that the 

 impairment of the reflex after removal of 

 the posterior lobe is not permanent and that 

 the reflex re-establishes itself after some 

 weeks, presumably because the remaining 

 portions of the neurohypophysis take over 

 the functions of the posterior lobe (Benson 

 and Cowie, 1956). That the neurohypophy- 

 sis participates in milk ejection would now 

 appear to be beyond question. 



The discovery of the role of the neurohy- 

 pophyseal hormones in milk ejection has 

 provided an explanation of some longstand- 

 ing clinical observations on what has been 

 termed the natural "sympathy" between 

 the uterus and the breasts. Thus the benefi- 

 cial effects of the suckling stimulus and the 

 occurrence of the "draught" {i.e., milk ejec- 

 tion) in causing uterine contraction after 

 parturition were emphasized over a century 

 ago by both Smith (1844) and Patcrson 

 (1844). 0})servations have also been made 

 on the I'cciprocal process of stimuli arising 

 from the reproductive organs apparently 

 causing milk ejection. In domestic animals 

 two such examples were mentioned by Mar- 

 tiny (1871). According to Herodotus, the 

 Scythians milk their mares thus: "They 

 take l)lowpipes of bone, very like flutes, and 

 put them into the genitals of the mares and 

 blow with their mouths, others milk. And 

 they say that the I'cason why thoy do so is 

 this, that when the marc's \-cins ai'c filled 



with air, the udder cometh down" (transla- 

 tion by Powell, 1949). Kolbe (1727) de- 

 scribed a similar procedure of blowing air 

 into the vagina used by the Hottentots when 

 milking cows which were normally suckled 

 by calves and in which, presumably, milk 

 ejection did not occur in response to hand 

 nnlking. A drawing depicting this procedure 

 from Kolbe's book was recently published in 

 the Ciba Zeitschrift (No. 84^ 1957) along 

 with a photograph of African natives still 

 using the method!-^ 



In 1839, Busch described the occurrence 

 of milk ejection, the milk actually spurting 

 from the nipple, in a lactating woman dur- 

 ing coitus. A satisfactory explanation of 

 these curious observations is now forth- 

 coming. Harris (1947) suggested that coitus 

 might cause the liberation of oxytocin from 

 the neurohypophysis and, within the next 

 few years it was demonstrated that stimula- 

 tion of the reproductive organs evoked milk 

 ejection in the cow (Hays and VanDemark. 

 1953) and reports confirmatory of Busch's 

 long forgotten observations also appeared 

 (Harris and Pickles, 1953; Campliell and 

 Petersen, 1953).^ 



C. MILK-EJECTIOX HORMONE 



There is much circumstantial evidence 

 to confirm the belief that the milk-ejection 

 hormone is oxytocin (see Cowie and Policy. 

 1957). Attemi)ts, however, to demonstrate 

 oxytocin in the blood after application of 

 the milking stimulus have given rather in- 

 conclusive results. Early claims that the 

 hormone could be demonstrated in blood are 



^ A similar drawing, also apparently from Kolbe '.•< 

 book, has been used in the campaign for clean milk 

 production! Heineman (1919) discussing sanitary 

 l^recautions in the cowshed says of the picture 

 "another picture shows a nude Hottentot milking 

 a cow while another one is liolding the tail of the 

 cow to prevent its dropping into the open pail. 

 This ])icture might well serve as a model to some 

 modern producers who do not take such precautions 

 and calmly lift the tail out of the milk with their 

 hands wlicn it hnjipens to switch into the pail." 



' W(- h;i\(' hi'cii able to find only one painting 

 illustrating this plienomenon. It is a picture by a 

 contemporary French painter, Andre Masson, en- 

 titled "Le Viol" and painted in 1939. It illustrates 

 in Masson 's personal idiom the act of rape and it is 

 interesting to note that a stream of milk is depicted 

 as being I'orcibly (\iected from one breast of the 



