242 



BOTANY 



ceases and abnormal processes of decomposition take place, whereby, as for instance 

 in alcoholic fermentation, alcohol and other products are formed. 



Intramolecular respiration commences as soon as the access of free oxygen to 

 the protoplasm is prevented, and continues until tin- latter is killed by the accumula- 

 tion of injurious products of decomposition. The sufficiently early readmittance 

 of oxygen may, however, permit the cell to resume its normal condition ,by re- 

 establishing ordinary respiration and 

 removing the accumulated products 

 of decomposition. 



Some plants endure the absence 

 of free oxygen badly and only for a 

 short time, others better and for a 

 longer period. Certain of the lower 

 plants (Bacteria, Fungi, Characeae) 

 can exist for a considerable time 

 without free oxygen, or are even able 

 under favourable conditions to find in 

 intramolecular respiration a complete 

 substitute for the ordinary oxygen- 

 respiration. This capability is so ex- 

 treme in some Bacteria that no trace 

 of free oxygen is necessary for their 

 existence, while some cannot live in 

 the presence of oxygen. To distin- 

 guish such specially adapted organ- 

 isms from those which depend for 

 their normal respiration on free 

 oxygen (aerobionts or aerobes) they 

 are termed anaerobionts or anaerobes. 

 The grades of independence of free 

 oxygen indicated above may be dis- 

 tinguished as temporary or faculta- 

 tive anaerobiosis and permanent or 

 obligate anaerobiosis respectively. 

 Plants which can store up substances 

 rich in oxygen (e.g. certain pigments) 



and at the expense of these live for 

 a time without an external supply 



Km. 211. Experiment to demonstrate respiration. 



The inverted tlask (IS) is partially filled with 



(lowers, which are held in plai-e by the plug of of oxygen may be distinguished as 



cotton (W). Through the absorption of the car- pseudo-anaerobes. 



bonic acid exhaled in respiration, by the solution Respiration as a Source of Energy. 



,,,' eaustie potash (^ the mercury^) rises in the _ he lnetabolic c , CQU . 



nerk of the flash. 



stituting respiration is a necessary 



concomitant of life may be inferred from the cessation of vital manifestations when 

 respiration is interfered with, and the association of more active life with increased 

 demands on the respiratory process. 



In respiration chemical changes occur leading to the setting free of energy. It 

 is hardly too much to say that it is the energy obtained by respiration which serves 

 to carry on and maintain the vital manifestations. Thus a specific vital energy is 

 obtained by means of respiration, which might be termed vital force were this term 

 not used in another sense ; sucli a supply of energy is not provided by other 



