Respiration experiments on Anura have, in the past, dealt chiefly with the adult frog. The importance of cutaneous respiration as determined by lung extirpation and subsequent CO, production and 0, consumption tests has been evidenced through the works of Spallanzani (1807)' Edwards (1824)' Regnault and Reiset ('49), Berg ('68), and Fubini ('81).
It remained for Klug ('84), however, to emphasize that accurate knowledge regarding the exact distribution of respiratory processes between lungs and skin can only be determined when the normal functions of each are simultaneously examined.
More recent work includes the studies of Dissard ('93), Marcacci ( '94), Couvreur ( '95)' and Krogh ( '04). Of these, the excellent paper of Krogh merits especial attention. I n addition to a critical and searching analysis of all previous work, this author perfected a n apparatus whereby the respiratory exchange of both skin and lungs could be studied under normal or' variable experimental conditions over long or short periods of time and without hindrance to the natural functioning of either organ. Krogh's results may be briefly summarized as follows : Carbenic acid is chiefly eliminated through the skin, while oxygen consumption is largely due 167