562 THE RESPIRATORY EXCHANGE 



stages of foetal life, and feeble respiratory movements might occur 

 within the uterus. The sudden assumption by the respiratory 

 centre of the capacity to send out rhythmic impulses to which 

 the respiratory muscles adequately respond has appeared a great 

 difficulty to some observers, for it was one of those leaps by which 

 Nature is said never to proceed. Against this might be brought 

 the suckling power of the newly born infant, were it not for the 

 fact that there is evidence that the foetus sucks, or at least 

 frequently swallows amniotic fluid during its intrauterine life. 

 May it not be that the respiratory centre as well as the respiratory 

 muscles gradually assume the power of rhythmic activity ; that 

 feeble respiratory movements, sufficient only to suck in and drive 

 out a little amniotic fluid or mucus from the naso-pharynx, are 

 present as a response to any considerable changes in the pressure 

 of oxygen and carbon dioxide during the last months of foetal 

 life ? Even if a little amniotic fluid were sucked into the trachea 

 it would be quickly absorbed ; it is sterile, is not toxic, and would 

 cause no mechanical disturbance, for the foetus is breathing by 

 means of the placenta. It is possible also that reflex inhibition 

 may occur, if the fluid penetrates too far into the naso-pharynx. 

 Ahlfeld has described certain intrauterine movements of the 

 foetus which appear to be due to the contraction of the respiratory 

 muscles ; they are rhythmic but irregular movements, with periods 

 of greater or less activity, and vary from 38 to 76 per minute ; 

 they can be felt under favourable circumstances in the region 

 of the mother's navel. In women in labour with their first child 

 it frequently happens that after the child's head is born, some 

 seconds, or even a minute or two, elapse before the body is expelled 

 by another forcible contraction of the uterus and muscles of the 

 abdominal wall. During this short interval respiratory move- 

 ments may occur ; in the nostrils may be seen bubbles of mucus 

 which are alternately blown out and sucked in. These respiratory 

 movements are of a very superficial nature, and may be easily 

 overlooked, so that the medical attendant may regard as the first 

 respiration that deep breath which is taken after the body is ex- 

 pelled, and is so often accompanied by a general movement of 

 the whole body and followed by a cry. Ahlfeld maintains that 

 the superficial respirations are similar to those intrauterine move- 

 ments which he and his pupils have investigated ; the so-called 

 first breath is not the first respiration, but the first deep breath 



