i54 



SCIENTIFIC NEWS. 



[Aug. 17, 1 J 



OUR KNOWLEDGE OF THE BACTERIA. 



(Continued from p. 109) 

 'THE forms which bacteria assume have been known for 

 a couple of centuries. Van Leeuwenhoek, of Delft, 

 an observer to whom we are indebted for an abundance of 

 microscopic discoveries, saw in the year 1683, merely 

 with single lenses of his own grinding, the now well- 

 known bacilli, micrococci, and spirilli. Further 

 observations showed the frequent and plentiful occurrence 

 of these beings in the most different localities and under 

 varied conditions. This circumstance, as well as the 

 apparent impossibility of preventing their appearance and 

 multiplication, gave rise to the thought that they were a 

 product of gencratio aeqitivoca. The first protest against 

 this view was raised by Spallanzani, in 1769. He found 

 that in infusions of plants contained in vessels which 

 had been closed and were then heated for a long time 

 the development of these micro-organisms — or as they 

 were then called animalcules — did not take place. But 

 on the free access of air which had not been heated they 

 promptly made their appearance. Hence he argued 

 that these microbia were not a product of spontaneous 

 generation, but were developed from pre-existing germs. 

 His opinion, long contested, was at last definitely and 

 victoriously established by the researches of Pasteur. 



The reason why these microbia were at first ranked 

 among animals was their swarming motion. Not until 

 the middle of the present century they were removed 

 from the animal kingdom by Perty, Cohn and Nageli in 

 accordance with their physiological properties and 

 grouped along with the fungi, under the name 

 Schizomycetes. It appeared that in certain essential 

 points they present the same vital relations as do fungi. 

 By reason of their want of chlorophyll they are not able 

 to decompose the carbonic acid of the atmosphere and 

 thus to obtain their supply of carbon. They are there- 

 fore restricted to a nutrient medium containing organic 

 substances, animal or vegetable, i.e., higher compounds 

 of carbon. Without such a medium they cannot exist. 



This is the case with the bacteria, which are never 

 able to decompose carbonic acid. Both ordinary fungi 

 and bacteria require a large proportion of nitrogen, 

 and are therefore limited to a nutrient medium rich in 

 that element. But not all bacteria and other fungi 

 require organic compounds of nitrogen; many of them 

 are able to assimilate even the simplest, such as nitric 

 acid and ammonia. 



Germs of bacteria susceptible of development may be 

 found everywhere in the air around us, in the water, 

 and in the superficial layers of the soil. Being suspended 

 in the air or adhering to particles of dust they are driven 

 by the wind against the surfaces of our walls, our furni- 

 ture, and our clothing, and are always to be found there. 

 Only on the loftiest peaks of snowy mountains and far 

 out upon the ocean, remote from the land, is the air 

 found free from such germs. The surface of our bodies, 

 in health, is covered with bacterial germs, and not 

 merely the external surface. With every breath of air 

 they find their way into the mouth, the nostrils, and the 

 respiratory organs. With every morsel we eat, and 

 with every drop we drink, bacterial germs enter the 

 mouth, the throat, the stomach, and the bowels. The 

 secretion of the mucous membranes, and the other 

 organic masses, which they here encounter, supply them 

 with scope for multiplication. We must not, however, 

 suppose that each and every kind of bacteria can prosper 



in any nutrient medium suited for bacteria in general. 

 On the contrary, bacteria have their likes and dislikes, and 

 every species requires particular kinds of nourishment. 



In the growth and the multiplication of bacteria there 

 occur a great series of phenomena all reducible to the 

 circumstance that the complicated compounds of which 

 their nutrient medium is composed are reduced to 

 simpler ones by their vital process. There are thus pro- 

 duced the simplest chemical bodies, such as carbonic 

 acid, hydrogen, hydrocarbons, sulphuretted hydrogen, and 

 ammonia. During this decomposition of the nutrient 

 medium we meet with the formation of the most varied 

 ferments. Thus there are bacteria which generate fer- 

 ments capable of converting saccharose into glucose, and 

 also starch into glucose, which dissolve (peptonise) 

 coagulated albumen and congealed gelatine, and which 

 coagulate milk. Other bacteria effect the most manifold 

 fermentations, and other?, again, occasion the different 

 phases of putrefaction, i.e., decompositions of nitrogenous 

 organic masses — with liberation of evil-smelling product 3. 

 These latter processes have been for the first time closely 

 studied by Pasteur. This able inquirer discovered the 

 important general part which the bacteria play in the 

 household of nature, reducing the complicated organic 

 compound (formed by the life of plants and animals 

 from inorganic substances) to the simplest states, and 

 thus completing the circulation of matter. Among the 

 chemical compounds produced in the vital process of 

 bacteria, a prominent place is due to the so-called 

 ptomaines, nitrogenous compounds of a basic character, 

 some of which, known as toxincs, are intensel}' poisonous. 



We may lastly mention that many bacteria can ela- 

 borate from the substance of their nutrient medium 

 colours, some of which are wonderfully beautiful. Others 

 develop in their transparent nutrient medium a splendid 

 fluorescence, whilst others give out in the dark a 

 phosphorescent light. 



Honours at the London University. — The honours 

 list of the London University Intermediate Examination in 

 Medicine, in Juty, shows a remarkable performance on the 

 part of the candidates sent up by the London School of 

 Medicine for Women. The totalnumberof places obtained 

 in honours by men and women was twenty-one, and of 

 these the men took eleven, and the women ten. Owens 

 College, Manchester, Middlesex Hospital, King's College 

 Hospital, St. Bartholomew's Hospital, each obtained one 

 place. From University College four successful candi- 

 dates obtained seven places, but from the London School 

 of Medicine for Women seven candidates obtained ten 

 places. It should be noted also that only five out of the 

 large number of men's schools have succeeded in getting 

 a place in the honours list, while a small and compara- 

 tively new school, such as the one for women, has secured 

 ten places. 



The New Rector of Leipzig University. — Dr. 

 Franz Hofmann, Professor of Experimental Hygiene 

 and Director of the Hygienic Institute in Leipzig 

 University, has just been chosen Rector of that seat of 

 learning. There is no higher name in Continental state 

 medicine than that of Professor Hofmann, as all who 

 remember the greeting accorded to him at the great 

 Vienna Congress of last year will understand ; and the 

 German journals, professional and lay, are hailing his 

 election as proof that public sanitation is becoming daily 

 more prized in the great centres of scientific education. 



