[Vol. 2 



460 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



regard to the reason why plants and animals thrive so 



much better 



media than in dis 



tilled water. Considering the period from about 1860 on 

 down to the present, the most important explanations offered 

 may be summed up under the following three heads : 



1. Lack of essential nutrients; 



2. 



3. 



sub 



organism 



immersed in the distilled water. 



Holding each of these views there has been a formidable 

 array of scientists at different periods, each group contend- 

 ing strongly to establish the correctness of its viewpoint. 



Among the earlier workers in the field may be mentioned 

 Boehm (75), Deherain (78), and others, who believed that 

 the lack of essential nutrients in the distilled water was 

 responsible for the resulting poor condition of the organism. 

 Boehm, for example, believed that calcium played a funda- 

 mental role in the metabolism of the plant, and that in its 

 absence certain processes, notably that of starch formation, 

 could not be carried on and that therefore deterioration re- 

 sulted. He also believed that calcium was necessary for the 

 transfer of the reserve materials from the cotyledons to the 

 formative organs. Deherain repeated Boehm 's experiments 

 and confirmed his results. 



Owing to the fact that even distilled water, which had been 

 unquestioningly regarded as pure, produced effects simulat- 

 ing toxicity, a great deal of attention has been given in the 

 past to the chemical and other properties of water distilled 

 from different kinds of apparatus and under various condi- 

 tions. On the animal side, workers, among whom may be 

 mentioned Kolliker ('56) and Nasse ('69), had early noticed 

 the injurious effects on tissues when the same were placed 

 in distilled water. Nasse, for example, found the deleterious 

 effect of distilled water about equal to that of the following 

 solutions : 2.5 per cent NaCl, 3.3 per cent NaBr, 3.7 per cent 

 NaoSO.i, and 5.0 per cent Nal. 



Nageli ('93), in his classical work published twelve years 

 after his death, found that very minute amounts of toxic sub- 



