58 PLANT PHYSIOLOGY 



198, 11. 19-30, for In addition to ... metabolism read According to MAZE 

 (1904), however, the appearance of citric acid is not connected with the 

 presence of oxygen, and does not arise from sugar, but from the proteid of 

 decaying cells, from which younger cells take up nitrogen when other nitrogen 

 compounds are deficient. WEHMER (LAFAR, Mykologie, IV, p. 248) contradicts 

 these statements. It is worthy of note, however, that the constitution of 

 citric acid, differing so much from sugar, makes its derivation from that sub- 

 stance difficult to conceive of. The formation of oxalic acid is also widely 

 distributed among higher plants, as may at once be concluded from the fre- 

 quency of the occurrences of calcium oxalate. While in earlier times the view 

 was held that the purpose of the oxalic acid was to unite with lime, and so 

 release the nitric acid which had been united with it to construct proteid, 

 it appears from the researches of AMAR (1902) and BENECKE (1903) that the 

 formation of oxalic acid arises in essentially the same way in green plants as 

 in Fungi. It is an intermediate respiratory product, capable of being further 

 broken down, but fixed in an insoluble combination when there is excess of 

 lime in the cell. Hence it is possible to induce the formation or disappearance 

 of oxalate in plants which normally contain it, if one presents to them not more 

 than the essential minimum of Ca(NO 3 ) 2 (AMAR), or if the nitric acid be pre- 

 sented to them in the form of a salt of ammonia (BENECKE). 



Apart from oxalic acid and oxalate the formation of acids takes place 

 in almost all plants, and although these arise occasionally, perhaps, during 

 synthesis, they appear frequently also in the course of hydrolytic splitting 

 (of fats and proteid), and so, for the most part, are connected with respiration. 



199, 11. 3-4, for at the moment when read where 



I. 17, after disposal read Obviously there are among leathery leaves 

 numerous transitions between normal leaves and the fleshy leaves of succu- 

 lents. Although BONNIER and MANGIN (1886) found the assimilatory co- 

 efficients in Ilex to be 1-24 instead of approximately i, that may be explained 

 by supposing that part of the assimilata arose from the organic acids produced 

 in decomposition. 



II. 27-8, for a convenient medium . . . normal read lies a simple means of 

 tripling the osmotic pressure. 



1. 38, for does not correspond to read far exceeded 



1. 41, for leading to read leading even to 



1. 46, for that seen only read that seen elsewhere 



200, 1. 21 P. 201, 1. 5, for in Fungi especially, and . . . contrasted with 

 plants read in Fungi especially. Aspergillus niger, for example, grows remark- 

 ably well, as is well known, with peptone as the source of nitrogen and sugar 

 as the source of carbon, and no indications are forthcoming that the peptone 

 is at the same time employed as respiratory material. But the fungus is able 

 to obtain what it needs, both of carbon and of nitrogen, when peptone is the 

 only organic body presented to it. Under these circumstances duties even of 

 the sugar must be undertaken by the peptone, but how that comes about we 

 do not know. It is known that peptone is split into amino-acids (BUTKEWITSCH, 

 1902), from which again ammonia even is split off in varying quantities accord- 

 ing to external conditions. Such a separation of nitrogen is indeed essential, 

 because certain of the combustion materials used by the fungus contain no 

 nitrogen. Whether the non-nitrogenous materials are alone used for respira- 

 tory purposes is not known ; it is not probable, however, for BUTKEWITSCH 

 found much less ammonia formed in other Mould Fungi than in Aspergillus, 

 and in this case also he was able to greatly restrain its formation by taking 

 care that the culture did not become acid. 



