664 SUMMARY OF CURRENT RESEARCHES RELATING TO 



the centre of a drop of water on a life-slide provided with a circtilar 

 air space, and covered with a cover-glass, the clear water surrounding 

 the opaque mass was filled in a short time with a protozoon be- 

 longing to the Protamoeb^. It was not difficult to see them, in 

 all possible shapes and sizes, creep out from the dark mass and 

 wander slowly toward the margin of the drop bordering the air space, 

 and the more numerous they were the more the air contained in the 

 water was consumed. This is a very convenient method, the author 

 adds, to which he has often resorted for bringing micro-organisms, 

 which live in hiding places, into view. It is air that they, like all 

 living beings, need for their existence, and the scarcer this becomes 

 in the isolated drop of water the more they approach from the centre 

 of the drop to its margin, which remains in contact with the air. 



The protamoebse observed differ from the ordinary species, not so 

 much in the peculiar shapes they assume as in the dark colour of 

 their contents, or rather in the presence of a dark, finely divided 

 substance imbedded in the otherwise transparent and colourless 

 gelatinous little mass. By the action of dilute hydrochloric acid, 

 under the development of a gaseous product (carbonic acid) the dark 

 contents are dissolved into a colourless fluid, while the bodies of the 

 protamcebse mostly assume more or less spherical forms, resembling 

 drops of oil. 



" Considering the great numbers in which these micro-organisms 

 are present, their peculiar mode of life by adhering to, and of loco- 

 motion by slowly creeping over a surface, their feeding by the simple 

 extension of their sarcode body over any material in their way, a 

 process very likely associated with some secretory function, it seems 

 quite probable that they exert an observable influence wherever they 

 happen to locate. This influence is probably of a mechanical as well 

 as of a chemical nature. When the material which fills out the furrows 

 is removed, the perfectly pure metallic surface of the copper is brought 

 to view, as if acted upon by the use of an acid. Thus, at first, as it 

 seems, the copper is dissolved in minute quantities, which afterwards, 

 by the interchange of the acid with the carbonic acid of the lime salt 

 contained in the water, forms a soluble organic lime compound and 

 carbonate of copper, the latter of which is deposited in the furrows. 

 That a portion of this as a comparatively indifferent material is taken 

 by the protamoebee is not surprising. They certainly do not feed on 

 the copper. Its presence is merely accidental, and the whole pheno- 

 mena, as I believe, should be looked upon from this point of view. 

 The species, even if brought into existence only by this peculiar 

 combination of circumstances, may be regarded as distinct, since it 

 has developed peculiar qualities and a mode of life of its own. The 

 origin of the protozoon is easily explained, and must be sought in the 

 rain-water which occasionally flows into the tank, carrying down 

 from the roof of the buildings microscopic forms of life." 



The author suggests that perhaps in other similar cases hitherto 

 ascribed to galvanic action or that of air and water, processes asso- 

 ciated with micro-organic life are of greater importance than has 

 been recognized. 



