POPULAR MISCELLANY. 



427 



gives an antiquity of not more than ten 

 thousand years to the end of the Glacial 

 epoch — a conclusion supported by the en- 

 largement of post-glacial valleys and the 

 silting up of small post-glacial lakes. 



Determination and Cnltivation of Bac- 

 teria. — Many scores of bacteria, says Prof. 

 John B. Roberts, in an address on the Rela- 

 tion of Bacteria to Practical Surgery, have 

 been, by patient study, differentiated from 

 their fellows, and given distinctive names. 

 Their nomenclature corresponds in classifi- 

 cation and arrangement with the nomencla- 

 ture adopted in different departments of bot- 

 any. Thus we have the pus-causing chain- 

 coccus {Streptococcus pyogenes), so called be- 

 cause it is globular in shape ; because it 

 grows with the individual plants attached to 

 each other, or arranged in a row, like a chain 

 of beads on a string ; and because it produces 

 pus. In a similar way we have the pus. 

 causing grape-coccus of a golden color (Sta- 

 phylococcus pyogenes aureus). It grows with 

 the individual plants arranged somewhat 

 after the manner of a bunch of grapes, and, 

 when millions of them are collected together, 

 the mass has a golden-yellow hue. The 

 difficulty of investigating these minute forms 

 becomes apparent when it is remembered 

 that under the microscope many of them are 

 identical in appearance, and it is only by 

 observing their growth when they are in a 

 proper soil that they can be distinguished 

 from one another. In certain cases it is 

 difficult to distinguish them by the physical 

 appearance produced during their growth. 

 Then it is only after an animal has been in- 

 oculated with them that the individual para- 

 site can be accurately recognized and called 

 by name. It is known, then, by the results 

 which it is capable of producing. Bacteria 

 may also be distinguished by their individ- 

 ual peculiarities of taking certain dyes. The 

 similarity between bacteria and ordinary 

 plants with which florists are familiar is 

 remarkable. Bacteria grow in animal and 

 other albuminous fluids ; but it is as essen- 

 tial to them to have a suitable soil as it is 

 for the corn or wheat that the farmer plants 

 in his field. By altering the character of 

 the albuminous fluid in which the micro- 

 organism finds its subsistence, these small 

 plants may be given a vigorous growth, or 



may be starved to death. The farmer knows 

 that it is impossible for him to grow the 

 same crop year after year in the same field, 

 and he is, therefore, compelled to rotate his 

 crops. So it is with the microscopic plants 

 which we are considering. After a time the 

 culture-field or soil becomes so exhausted 

 of its needed constituents, by the immense 

 number of plants living in it, that it is unfit 

 for their life or development. Then this 

 particular form will no longer thrive ; but 

 some other form of bacteria may find in it 

 the properties required for functional activ- 

 ity and may grow vigorously. Again, there 

 are certain bacteria which are so antagonis- 

 tic to each other that it is impossible to 

 make them grow in company or coexist in 

 the blood of the same individual. An ani- 

 mal inoculated with erysipelas germs can 

 not be successfully inoculated immediately 

 afterward with the germs of malignant pust- 

 ule. As the horticulturist is able to alter 

 the character of his plants by changing the 

 circumstances under which they live, so can 

 the bacteriologist change the vital proper- 

 ties and activities of bacteria by chemical 

 and other manipulations of the culture-sub- 

 stances in which these organisms grow. 

 The power of bacteria to cause pathological 

 changes may thus be weakened and attenu- 

 ated ; in other words, their functional power 

 for evil is taken from them by alterations in 

 the soil, and vice versa. 



Properties of Peroxide of Hydrogen. — 



Peroxide of hydrogen has been a subject of 

 experiment by Dr. B. W. Richardson, chiefly 

 with regard to its medical uses, for more 

 than thirty years. He regards it as a solu- 

 tion — although it may be made to take on the 

 gaseous form — and as consisting of water 

 containing, according to strength, so many 

 atmospheres of oxygen ; or as an oxygen at- 

 mosphere in solution. It is not, however, a 

 mere mixture, but a peculiar chemical com- 

 pound. The oxygen can be made to accumu- 

 late, volume by volume, until the volume of 

 water can rise to ten, twenty, thirty, and 

 some say even more than a hundred volumes 

 of oxygen, before complete saturation is 

 reached and a volatile body is formed. The 

 combination of the added oxygen in hydro- 

 gen peroxide is stable in the presence of some 

 substances, unstable and easily evolved in the 



