198 



THE AMERICAN MONTHLY 



[October, 



Bacteria. — Dr. Charles S. Dolley 

 has published a translation of an ar- 

 ticle by Dr. Ferdinand Cohn, on 

 "Bacteria, the smallest of Living 

 Organisms." It is in the form of a 

 pamphlet of thirty pages, with one 

 lithograph-plate. We have already 

 directed the attention of our readers 

 to Dr. Magnin's work on the Bacteria, 

 translated by Dr. Sternberg, which is 

 the most useful book we have in 

 English treating of this subject, but 

 for the microscopist who merely de- 

 sires a general knowledge of the forms 

 he meets with, sufficient to enable him 

 to say whether they are Bacterium^ 

 or Bacillus, or Vibrio, etc., we can 

 heartily commend this pamphlet. 



The distinctions made by the author 

 result in six genera, as follows : — 

 Micrococcus ball, or egg-shaped, 

 Bacteriufu short, rod-like. 

 Bacillus straight, fibre-like, 

 Vibrio wavy, curl-like, 

 Spirillum, short, screw-like, 

 Spirochete long, flexible, spiral. 

 The rapidity of their multiplication 

 is astonishing. It has been calculated 

 that a single one will give rise to a 

 progeny of 16,770,220 in a one day, 

 and in two days the number will be 

 281,500,000,000 ; in a week the num- 

 •ber could only be expressed by figures 

 of fifty-one places. 



The importance of these minute 

 organisms should not be under-estim- 

 ated ; Dr. Cohn has indicated their 

 role in effecting decomposition in 

 these words : — 



" The whole arrangement of nature 

 is based on this, that the body in which 

 life has been extinguished succombs 

 to dissolution, in order that its ma- 

 terial may become again serviceable 

 to new life. If the amount of material 

 which can be moulded into living 

 beings is limited on the earth, the 

 same particles of material must ever 

 be converted from dead into living 

 bodies in an eternal circle ; if the 

 wandering of the soul be a myth, the 

 wandering of matter is a scientific 

 fact. If there were no bacteria, the 

 material embodied in animals and 



plants of one generation would, after 

 their decease, remain bound, as are 

 the chemical combinations in the 

 rocks ; new life could not develop, 

 because there would be a lack of 

 body-material. Since bacteria cause 

 the dead body to come to the earth 

 in rapid putrefaction, they alone cause 

 the springing forth of new life, and 

 therefore make the continuance of 

 living creatures possible." 



The pamphlet concludes with some 

 speculations concerning the origin of 

 life upon the earth, in which it is 

 suggested that the germs of bacteria 

 may have come to us from the cosmic 

 dust, and thus the bacteria became 

 the first living organism on this globe, 

 from which all other forms have since 

 developed. 



o 



Pond-Life. — We have recently re- 

 ceived from Mr. A. D. Balen, of 

 Plainfield, N. J., who, as already 

 mentioned in these columns, is ar- 

 ranging to supply microscopists with 

 living specimens, several bottles, the 

 contents of which have been very 

 interesting. At the present time we 

 have some of the beautiful zoophyte 

 Pectinatella magjiifica, which has been 

 growing in a small bottle for several 

 days. This zoophyte grows in gela- 

 tinous masses of more than a foot in 

 diameter, but it is useless to endeavor 

 to keep the large masses in jars. 

 Small colonies, about a quarter or 

 half of an inch in diameter, attached 

 to water-plants, should be selected 

 for this purpose, and they will live 

 very well in a sufficient quantity of 

 water. Under a low power objective 

 one of the small colonies is a very 

 beautiful object. The double row of 

 tentacles belonging to each individual, 

 covered with active cilia which pro- 

 duce strong currents in the water, 

 drawing the food to the animals, are 

 arranged on a horse-shoe shaped 

 disc, which is a characteristic of the 

 order Hippocrepia. Under a ^-inch 

 objective the cilia on the tentacles are 

 readily seen. It is said that this ani- 

 mal is not found in Britain. 



