THE REGULATION IN HEALTH AND DISEASE 561 



that in cases of very protracted labour the full-term foetus has 

 given respiratory movements in the uterus itself, for after death 

 amniotic fluid, foetal hair or lanugo, and meconium have been 

 found in the trachea and bronchi. Newly born infants and 

 animals often do not draw their first breath for several seconds, 

 it may be two minutes, after birth, notwithstanding the exposure 

 of the body and the absence of any injury. Ahlfeld ( 32 ) has shown 

 that infants delivered into a bath at the temperature of the 

 mother's body do not delay their first breath. 



Preyer( 33 ) maintained that the true cause of the first respira- 

 tion was cutaneous stimulation in some form or other, that venosity 

 of the blood in itself was no stimulus to the respiratory centre 

 in the medulla oblongata, although to a certain extent it raised 

 the excitability of the centre for the cutaneous stimuli. The 

 evidence against this view has already been given so far as sensa- 

 tions of cold are concerned ; as regards mechanical stimulation 

 it is well known that if the placental circulation be intact, the 

 full-term foetus may be subjected to much manipulation in cases 

 of complicated labour or false presentations without any danger 

 of causing it to breathe prematurely within the cavity of the 

 uterus. Cohnstein and Zuntz removed a foetal sheep from the 

 uterus without damage to the placental circulation ; stimulation 

 of the skin, even blowing air into the nostrils, did not cause it to 

 draw a breath, but only evoked general reflex movements. The 

 premature lamb sucked the experimenter's finger when it was 

 placed in its mouth, and from time to time spontaneously moved 

 its body, but it did not draw a single breath until the umbilical cord 

 was tied, when it forthwith commenced to breathe. 



Cutaneous stimulation may be, and probably is, an accessory 

 cause of the first breath, but it is obvious that others must be 

 the effective ones. An increase in the carbon dioxide or a decrease 

 in the oxygen of the blood will act as a stimulus to the respiratory 

 centre. Such a condition will occur when the infant is born and 

 the umbilical cord is severed. During the last stages of labour 

 the placental circulation is disturbed but does not cease, for the 

 amniotic fluid behind the body of the foetus will prevent the 

 obliteration of the cavity of the uterus and the complete separa- 

 tion of the placenta. If an increase of carbon dioxide and a 

 decrease of oxygen in the blood be the stimuli for respiration, 

 one would expect them to be sometimes effective during the later 



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