6 io PRINCIPLES OF GENERAL PHYSIOLOGY 



anaesthesia, as by drugs, heat, asphyxia, and so on, are essentially the same physico-chemical 

 process. He also clearly pointed out that the ordinary phenomena of asphyxia have nothing 

 to do with those of narcosis (p. 96). 



Loewe (1913), as the result of detailed investigations of the relation of 

 narcotics to lipoids, came to the conclusion that the cell membrane consists of 

 a complex colloidal system of hydrophile colloids together with lipoids, and 

 that the narcotics are adsorbed by the latter, with the result that their hydrophile 

 nature is changed into a hydrophobe nature, or one that behaves as such, 

 although no water is lost. Hence the decrease of permeability found experi- 

 mentally as the accompaniment of typical narcosis, as opposed to the increase 

 associated with lethal action. There may also be a diminution of "elective" 

 permeability, resulting in diminution of potential difference and injury to 

 "specific" functions of the membrane. But it is difficult to attach very 

 definite meaning to the last statements. 



ANAEROBIC EXISTENCE 



We have seen that certain organisms, both animal and vegetable, such as 

 some bacteria and nucleated red blood corpuscles, are not killed by deprivation 

 of oxygen, although no oxidation proceeds and cell activities are suspended. 

 Recovery takes place on admission of oxygen. In other cases, such as intestinal 

 worms, the leech, and yeast cells, chemical activities of a special kind proceed, 

 together with certain manifestations of life, in absence of oxygen. A further 

 condition is that of certain bacteria, which are killed by oxygen and are 

 capable of existence only in its absence. Thus we have facultative and 

 obligatory anaerobiosis. 



The manifestations of life require the supply of free energy. This is 

 usually obtained from oxidative reactions, and the interesting problem arises, 

 How is it obtained in absence of oxygen ? 



Perhaps the best example to start with is that of the mould, Mucor 

 racemosus, which, as shown by Pasteur (1876, pp. 130-132), in the presence 

 of oxygen burns up glucose to carbon dioxide and water, but when submerged 

 and deprived of oxygen, certain morphological changes occur and it now 

 forms alcohol and carbon dioxide from glucose. 



Yeast. We have seen that no growth takes place in absence of oxygen, 

 but that the fermentation proceeds. In this fermentation, in which sugar is 

 split into alcohol and carbon dioxide, there is production of heat ; so that we 

 may put it in this way, the combination of part of the carbon with oxygen 

 to form carbon dioxide sets free more energy than is required to make up the 

 difference between the heats of combustion of alcohol and of sugar. There is, 

 then, energy at the disposal of the organism for what activities it is capable 

 of, if this energy can be made use of. The reaction from glucose to alcohol 

 probably passes through several stages, similar to those given on page 273. 



Putrefactive Organisms. Pasteur (1861) showed that certain organisms, 

 responsible for butyric acid formation in putrefaction, were actually killed by 

 oxygen, although, presumably, their spores are able to withstand its presence. 

 In a protein undergoing putrefaction, it was shown by Hoppe-Seyler (1887) 

 that the chemical products of putrefaction are different when the process pro- 

 ceeds with or without air. In the presence of air, aerobic organisms develop 

 at the surface, while anaerobic ones grow in the depths. In presence of oxygen, 

 carbon dioxide, water, and ammonia are formed ; in its absence, hydrogen, 

 marsh gas, leucine, and tyrosine. Nencki (1904, 1, p. 376) showed that certain 

 aromatic derivatives, phenyl-propionic acid, parahydroxyphenylpropionic acid, 

 and skatol-acetic acid, together with lower fatty acids, butyric, caproic, etc., 

 were formed in anaerobic putrefaction. It is chiefly to these lower fatty acids, 

 together with indol and skatol, that putrefactions owe their objectionable 

 smell. Methyl-mercaptan is also sometimes present. Decarboxylation of 

 amino-acids occurs, giving rise to various amines, and, from diamino-acids, 

 putrescine and cadaverine. (tetra- and penta-methylene-diamines). 



