ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 429 



(in the most cases granules of wheat), are observed. In a short time 

 numerous mobile minute bodies are seen, the mobility of which seems 

 at first to be the well-known molecular motion, but is soon turned into 

 the most active bacteroid motion. By using a higher power (500 diam.) 

 we observe in the agglomeration various forms of bacteroid life, very 

 well recognizable both by their constant relations of size and shape, 

 and by the mode of motion peculiar to the various bacteroid types. 

 There are rod-shaped Bacteria with oscillating and spiral motion, and 

 globular bacteria with the peculiar rocking-oscillating motion. Some- 

 times all these forms of bacteroid life are found on one and the same 

 coin ; in most cases there are found on one coin more especially 

 globular Bacteria, on another coin more rod-shaped Bacteria. The 

 globular forms make up in the case of all coins the principal con- 

 stituent of bacteroid life in the incrustation. Spirillum is not found 

 very often, but by searching after it, and dispersing the substance under 

 the cover-glass it is sure to be found in a great many cases. Of 

 Bacillus, four to six divided rods of • 0055-0 • 0074 mm. in length are 

 found on all silver, copper, and bronze coins. The automobile motion 

 of the bacteroid bodies, lasting for many hours, is instantly stopped 

 with one drop of a solution of iodine or of concentrated glycerine 

 placed on the margin of the cover. 



Of the unicellular algee in the incrustations of nearly all the coins 

 hitherto examined, I have distinguished till now two very distinct 

 and constant types, the characteristics of which are so clear and 

 constant, that they can be identified with known types of algae and 

 classified in the system of algse. There is one most minute Chroococcus 

 and one unicellular alga which I think very nearly allied to the 

 Palmellacese, The slightly tinctured cells of this Chroococcus of 

 • 00925 mm. diam,, form minute globular bodies, composed of 4, 8, to 

 12 cellules. These globular bodies are clustered together, forming 

 minute irregular masses, 0'02 mm. diam. The Palmellaceous alga 

 has many times larger, thick-walled cells ; the contents of which are 

 mostly intensely tinctured. The cells are found in all states of 

 division from two to more. Of the Palmellace^ Pleurococcus is the 

 type, coming the nearest to this new alga. The cells in the undivided 

 state are found 0* 009-0 "01 mm. diam. The thickness of the wall 

 of the cells is equal nearly to 1/10 the transverse diameter of the 

 cells. The cells in their many-divided state do not exhibit the same 

 regular and symmetrical disposition of the daughter-cells as the 

 typical Pleurococcus (P. vulgaris). 



In addition to these organisms there are found in the incrustations 

 of the coins (besides undeveloped fungoid hyphse), spores of various 

 Cryptogams of various size and shape, belonging to the Hyphomycetes 

 and the Coniomycetes. 



It may be concluded from the constancy of the characteristics and 

 of the occurrence of these two unicellular organisms, that their 

 occurrence is a spontaneous one, just as is the case with a large 

 number of these organisms of the lowest state, concerning both living 

 and dead matter ; in other words that these organisms have to be 

 considered not as accidentally adherent substances but as organisms, 



