Effect of Arsenic Compounds 63 



poisons, the optimal quantity for algae being lower than that for fungi. 

 Protococcus showed a possible stimulus when grown in concentrations 

 of potassium arsenate varying from '00002 '0005%. This possible 

 stimulus is interesting in view of the failure to observe stimulation in 

 higher plants by minute traces of arsenic. 



2. Fungi. 



The effect of arsenic on fungi is of special interest in that it has a 

 direct bearing upon hygienic and commercial interests. Gosio (1892, 

 1897, 1901) found that certain of the fungi, Mucor mucedo and Asper- 

 gillus glaucum, will grow on various arsenic compounds and exercise a 

 reducing influence on them. These moulds attack all oxygen com- 

 pounds of arsenic including copper arsenite, and develope arsenical 

 gases. Sulphur compounds of arsenic are not influenced by these fungi. 

 The same moulds would, if cultivated in soil containing arsenic, de- 

 velope hydrogen arsenide. Penicillium glaucum has such a strong and 

 definite action on arsenic compounds that he states that there is no 

 doubt of the possibility of poisoning by arsenical gas in a room hung 

 with paper containing arsenic. The compounds are so extraordinarily 

 potent that if a mouse is placed in a vessel in which the mould is strongly 

 developed in the presence of arsenic, it dies in a few seconds. Peni- 

 cillium brevicaule uses the element in its development as a food substance. 

 If material containing arsenic is placed in contact with dead fungi no 

 reaction occurs. The life activity of the mould is evidently necessary 

 for the reaction by which the arsenic-containing gases are liberated. 

 Csapodi (1894) put forward the earlier results of Gosio and noted that 

 the so-called arsenical fungicides do not only fail to kill the mould fungi 

 but actually favour their development. This action explains why wall- 

 paper containing arsenic is so disadvantageous in a room. Abba (1898) 

 severely tested Gosio's method of detecting arsenic by means of growths 

 of Penicillium brevicaule, whereby arsenic gases are liberated, vindicating 

 the method completely, and establishing the test as an exceptionally 

 delicate one. Segale (1904) applied the same method to the detection 

 of the presence of arsenic in animal tissues. 



Ono (1900) grew Penicillium cultures with solutions of potassium 

 arsenate and found no important differences either of depression or 

 stimulation. Orlowski (1902-3) stated that small doses of arsenic 

 (1/10001/100 % Sodium arsen l ) stimulate the growth of Aspergillus 



1 The exact compound is not specified in the abstracted paper, ^7 jfo- % Natr. Ars. 

 being given. 



