Introduction 25 



The new procedure has already been employed to determine the quantum 

 requirement of photosynthesis with only one irradiated vessel. It has also been 

 employed to determine the oxygen consumption of Cancer cells ; the respiration 

 of these cells is determined only inaccurately by means of the two-vessel method 

 because of the cells' large aerobic fermentation. 



The new trough vessels are conical and have insets that are located within the 

 upper third, rather than at the bottom, of the main vessel. These trough insets 

 are no longer shaped like cylinders but rather like flat troughs. They are connected 

 to a sidearm, from which substances may be introduced into the trough; a second 

 sidearm is connected to the main vessel rather than to the trough. 



If we mix in the trough via its sidearm, substances that are neutral and that 

 do not become alkaline until they are mixed, we can determine the carbon dioxide 

 content of the manometric vessel. If the cell Suspension in the main compartment 

 of the vessel is fvrst acidified via the second sidearm, and the contents of the trough 

 are only then made alkaline, the total carbon dioxide in the manometric vessel 

 can be determined. If we mix in the trough substances which, upon contact 

 with one another, give off oxygen without a simultaneous change in the pressure 

 of carbon dioxide — for instance, catalase and hydrogen peroxide — we can make 

 the transition from anaerobic to aerobic conditions without opening the vessel. 

 If, on the other hand, we mix in the trough substances that, upon contact with 

 one another, absorb oxygen, without the reaction becoming alkaline, we can make 

 the transition from aerobic to anaerobic conditions without opening the vessel. 



Of the application of trough vessels to date we should like to mention the meas- 

 urement of the fixation of CO-2 in green cells, a determination that can be made 

 much more reliably and precisly by the use of through vessels compared to the 

 usual C 14 methods. We should further like to mention the measurement of the 

 uptake of carbon dioxide by Chlorella as a result of the transition from anaerobic 

 to aerobic conditions, as well as the measurement of the evolution of carbon dioxide 

 by Chlorella on transition to anaerobic conditions. In addition, we should like to 

 mention the measurement, in a Single vessel, of the retention of carbon dioxide 

 and lactic acid. 



III. Radiation measurement (Bolometer) 



The bolometer in use today was developed at the Physikalisch-Technische Reichs- 

 anstalt by Lummer and Kurlbaum. It is an instrument that has a great past; 

 with it Lummer and Pringsheim 4 measured the radiation of black bodies. From 

 their experiments in 1900, Planck 5 derived his formula for radiation in 1900 and 

 calculated the constant h (h = 6.55 • 10~ 27 erg • sec, as compared to today's value 

 of h = 6.63 • 10 --' erg • sec). It is the same instrument with which Emil War- 

 burg 6 in the years 1911 to 1930 laid the foundations of quantitative photochemistry. 

 The bolometer has one advantage that distinguishes it from all other instruments 

 for the absolute measurement of radiation : If one permits a beam of light to fall on 

 the platinum Strips of the bolometer and then shifts the beam over the surface of the 



