72 PLANT PHYSIOLOGY 



higher organisms. The mode of decomposition of these bodies (comp. HAHN 

 and SPIECKERMANN in LAFAR, III. 85) appears to be as follows : they decom- 

 pose into amino-acids, such as we have already met with in germination ; from 

 these ammonia is next split off and the remaining acid is transformed into 

 simpler and simpler bodies by oxidation and reduction ; finally, H, methane, 

 carbon-dioxide, free nitrogen and ammonia are produced. Since, however, 

 sulphur, and phosphorus as well, are present in proteids, sulphuretted hydrogen 

 and phosphoric acid are also end-products. In the formation of these bodies 

 numerous aerobic and anaerobic Bacteria and Fungi are concerned and many 

 very characteristic by-products among the aromatic amino-acids make their 

 appearance, the best known of which are indol and skatol. We need not go 

 further into the matter, however, for the chief point we desire to establish is 

 only that, in the long run, nitrogenous and non -nitrogenous organic bodies are 

 transformed into simple inorganic compounds, which are in part directly, in 

 part indirectly (due to the agency of micro-organisms which we shall study in 

 the next lecture), made to serve once more as nutrients to the autotrophic 

 green plant. 



P. 220. Lecture XVIII is XVII of the 2nd German Edition with title 



OXIDATION OF SULPHURETTED HYDROGEN, HYDROGEN, 

 METHANE, AND AMMONIA BY BACTERIA. CARBON-DIOXIDE 

 ASSIMILATION IN THE ABSENCE OF LIGHT AND CHLOROPHYLL 



220, 11. 26-49, /OP At t ne conclusion of ... 'sulphur-bacteria' read In the last 

 lecture we became acquainted with certain processes which led to the formation 

 of sulphuretted hydrogen, viz. the reduction of sulphates and the putrefaction 

 of proteid ; but there are other processes taking place in nature, which we need 

 not go into here, which also lead to the development of sulphuretted hydrogen. 

 We know, however, that this substance is quite unsuitable as a source of sulphur 

 to higher plants, for these forms make use of sulphates exclusively. 



221, 11. 7-8, delete [OMELIANSKI . . . sulphur-Bacteria.] 



1- 38, for containing sulphuretted hydrogen read to which H 2 S has been 

 added, 



222, 1. i, for a read an approximately 



1. 7, for On the fluid being renewed read On ceasing to renew the fluid, 



I. n, after reach read rapidly 



II. 14-19, for In a mud swamp ... its existence read In a mud swamp, 

 just as in sulphur springs, it always attempts to find a region with an optimum 

 oxygen tension, inhabiting level places subject to flooding and avoiding deeper 

 hollows. Moreover, in determining its distribution not only oxygen but also 

 sulphuretted hydrogen plays a part, for the organism can tolerate only a definite 

 and not really high concentration of that substance. 



1. 47, for diminished read accomplished 



1. 54, for absent . . . cases read impossible for most living beings. 



223, 1. 5, for i. e. in infinitesimal quantity read i. e. infinitesimal quantities. 



I. 22, for (p. 229) read (at least so we must suppose for the present ; comp., 

 however, p. 229). 



II. 26-33, for To Beggiatoa . . . with regard to them read To Beggiatoa is 

 allied, in the first place, the genus Thiothrix, which according to WINOGRADSKY 

 may be described simply as a fixed Beggiatoa. A reinvestigation of this form 

 is desirable, however, for the presence of sulphur in it has recently been called 



