Morphogenesis and metabolism: studies with the cartesian diver ultramicromanometer IV. Respiratory quotient of the regions of the amphibian gastrula

Abstract

No method has so far been published for obtaining the respiratory quotient of small pieces of tissue or living organisms the total gas turnover of which in the available experimental period is likely to be of the order of 1/10 cu. mm. In the present paper we shall describe such a method and give details of the results obtained with it on single isolated pieces of the regions of the amphibian gastrula. Dixon (1934) and others have given sufficient reasons for rejecting all methods which do not determine the oxygen consumption and the production of carbon dioxide on the same piece of tissue so that the simplest method on the usual large scale is that of Dickens and Šimer (1930) in which annular cups are used. As this necessitates the use of phosphate buffer solutions, which are regarded as unphysiological for work with mammalian tissues, the later more complicated methods in which bicarbonate is employed came into general use. For the present problem, however, in which thee amphibian embryonic tissues studied remain perfectly normal in Holtfeter solution or even tap or river water, the difficulties caused by bicarbonate were avoided. At the same time, we believe that is should be by no means impossible to adapt the driver manometer to measurements of respiratory quotient even in bicarbonate medium.