Mar. 1901.] BOTANICAL SOCIETY OF EDINBURGH 55 



molecule, the greater the number of phases of preparation 

 that must be passed through. In autogenetic development, 

 the cycle includes only a single development, which is at 

 once the phase of preparation and maturation. " Multi- 

 plication is the result of the phases of preparation, while 

 reproduction is the final result of the phase of maturation." 

 In dealing with the 'phy&iology of the hiomolecnle, the 

 author takes us over ground of much interest to botanists, 

 and enables us to form exact conceptions of such functions 

 as respiration, starch formation, function of chlorophyll, 

 and secretion. Botanists are accustomed to distinguish 

 the respiratory from the food oxygen in plants, but with 

 this theory there is no such distinction — it is all food 

 oxygen. Eespiration, thus, is merely one of the episodes 

 of nutrition, just as the assimilation of carbon, hydrogen, 

 and nitrogen represent others ; and since all living sub- 

 stance contains atoms of oxygen in its molecules, respiration 

 is a phenomenon common to all organisms. The element, 

 unlike the other food elements, is absorbed in the uncombined 

 condition. This uniqueness, and the easy demonstrability 

 of the process, have led to its being regarded as a process 

 apart, and to its being dignified by a special name. Eespira- 

 tion being interpreted in a broad sense as the absorption of 

 oxygen free or combined, the so-called anterobia respire, 

 inasmuch as though they do not absorb the free element, 

 they absorb it in the combined state. The suggestion is 

 made that the biomolecules of anaerobic bacteria resemble 

 certain easily oxidisable substances, which combine not only 

 with free oxygen, but, on account of their great affinity for 

 this element, can abstract it from other substances with 

 which it is combined. The author epitomises his conception 

 of the phenomenon of respiration in the following words: — 

 " Eespiration is not a combustion, it is an oxidation." By 

 combustion is meant here oxidation of carbon atoms. If 

 two atoms of oxygen are absorbed by a biomolecule con- 

 taining atoms of carbon, these may link on to one atom 

 of carbon, and so satisfying its four valencies, unlink it from 

 the biomolecule, when it will escape as carbon dioxide. 

 If these were the real facts of respiration, the oxygen would 

 be continually abstracting atoms of carbon from the bio- 

 molecule, and the latter would gradually be destroyed. In 



