i 7 6 



THE ENERGY OF THE LIVING PROTOPLASM. 



oxidation products, as carbohydrates from fats in plants,' 1 and it 

 helps to prepare from different materials the necessary starting 

 groups for protein formation (cf. Chap. V). 



While a unicellular organism obtains the necessary oxygen 

 by a simple diffusion process, more or less complicated contri- 

 vances are necessary to provide the interior cells of multicellular 

 organisms with air. Stomata, lenticells, and intercellular spaces 

 serve this purpose in the vegetable kingdom ; tracheitis, gills, 

 lungs, haemoglobin, in the animal kingdom. Movements of the 

 abdomen and thorax in insects, of the gills in aquatic animals, 

 of the chest in lung-bearing animals, maintain the exchange of 

 oxygen against the resulting carbon dioxide. Certain insects, as 

 the larvae of the Libellulidcv, and even a fish {Cobitis fossilis) , exhibit 

 the remarkable exception, of carrying on their respiration by the 

 intestines, which are provided for this purpose with innumerable 

 blood vessels. 



Not all organisms, however, produce their physiological 

 energy by respiration ; the fermentative organisms gain it with- 

 out the aid of oxygen, by decomposition of organic matter, (2) 

 Bacteria can utilise various hydroxy-acids, proteids, poly- 

 valent alcohols and sugars, while the )'easts certain kinds of 

 sugar only. We have here the case of the so-called intramolecular 

 respiration before us, one which yields considerably less energy 

 than normal respiration. Also certain animals can for a limited 



(1) The formation of organic acids is also due to respiration, viz., to an imper- 

 fect oxidation of sugar in most cases. An interesting example is furnished by the 

 flowers of Ipomaa triloba, which are blue in the morning and remain so during 

 cold foggy, and rainy days, but turn red on warm bright days. Since this change 

 from blue to red can also be easily accomplished by acids, we must assume that the 

 increased respiration on warm days causes the production of acids. 



(2) The fact that bacteria can be deprived of their fermentative faculties, 

 without their life being impaired and thus be turned from anaerobs into obligate 

 atrobs, has led me to the view, that there exists a special organoid in those organisms 

 endowed with fermentative action. This would, to a certain degree, be analogous 

 to the chloroplasts of green plants ; the latter prepares suitable material for growth 

 from carbonic acid, while the former prepares it by decomposing various organic 

 matters. A small fraction of these fermenting compounds does not appear in form of 

 fermentation products, but in that of new cells of the fermenting organism. We see 

 therefore, here also a double part played, viz, that of liberating energy and that of 

 preparing the necessary groups for protein formation. Cf. O. Loew, Centralbl f. 

 Bacteriologie 9, Nr. 22. 



