197 



in his publication: „Bijdrage tot de kennis der cliemische samen- 

 stelling van het duinwater in verband met de geo-mineralogisehe 

 gesteldheid van den bodem." The writer sajs (p. 50) that at such 

 a great depth bacterial influence on the oxidation of organic matter 

 seems to be out of the question and he suspects manganese salts to 

 act as oxjgen-carriers. Further on (pg. 62) the writer sajs : ,,•••• I 

 do not think that Miciospira desidfuricans occurs at such a depth 

 as has to be assumed when ascribing sulphate-reduction oidy to 

 this micro-organisme". 



On pag. 5J the author records some experiments which go to 

 show that manganese can transmit oxygen from the sulphates to 

 an organic compound such as hjdrochinon. To conclude from this 

 that the oxidation of organic matter at the lower depths in the soil 

 could occur in the same way, seems to me hardly admissible unless 

 experimental evidence be brought forward that biological oxidation 

 is out of the question. Such evidence has not been [)roduced as yet. 

 It may be deemed surprising that the author, who, as appears from 

 the passage in his publication that we quoted just now, had taken 

 cognizance of the bacteriological sulphate reduction has omitted to 

 inquire into it. This is the more surprising since on the ground of 

 its anaerobic behaviour Microspira desulfuricans is adapted to living 

 at greather depths in the soil. 



The evidence produced by our investigation set forth in the 

 preceding paragraphs, by which it has been established that sulphate- 

 reduction is of common occurrence at the greater depths underneath 

 the dunes, warrant the conclusion that oxidation of organic matter 

 can be effected by Microspira desulfuricans, without the additional 

 influence of manganese compounds. 



§ 9. The tran.{formation of sulphate in the clay-containiiig 



soil of the dunes and sulphate-reduction by Microspira 



desulfuricans. 



The "Koninklijke Academie van Wetenschappen te Amsterdam" ') 

 has brought forth a re|)ort on the question to what the presence of 

 so called Artesian water in the dune-soil is due, in a preliminary 

 advice from G. A. F'. Molengraaff and Eug. Dubois. In an enume- 

 ration of the chemical properties of dune-water the report contains 

 the following statement: \ 



^) Verslag v. d. gewone vergaderingen der Wis- en Natuurk. Afd. Vol. XXX, 

 p. 212. 



