NATURE 



46: 



THURSDAY, SEPTEMBER 13, 1900. 



BACTERIOLOGY. 

 The Structure and Functions of Bacteria. By Alfred 

 Fischer, Professor of Botany at the University of 

 Leipzig. Translated into English by A. Coppen Jones. 

 Pp. viii + 198. (London : Clarendon Press, 1900.) 



THE first two chapters are concerned with the mor- 

 phology of bacteria, and the subject is most ably 

 dealt with, as mi>>ht be expected from so talented a 

 botanist as Prof. Fischer. Nevertheless, these are not 

 the chapters which strike one as of exceptional interest 

 or importance, because they treat of matters discussed 

 n every text-book of bacteriology, and afford but little 

 new information. 



Chapters iii. and iv., under the title of "Taxonomy," 

 deal with the question of species and variability among 

 bacteria ; the involution and attenuation of microbes ; 

 the systematic position of bacteria and their classification, 

 rof. Fischer points out that the heated controversy on 

 he " species question " rests on our different conception 

 of pieogony and pleotnorphisni among bacteria. Pleo- 

 morphism in its true sense does not exist among bacteria 

 according to Fischer, and mutability of function (other 

 than of a temporary character) is also denied by him. 

 Thus he asserts positively that " It has not been hitherto 

 possible to entirely suppress a single biological character 

 in any species." We are inclined to take a less dogmatic 

 position as regards the suppression of a biological 

 character, while fully agreeing with the author that the 

 attainment in our cultures of ar^w/V^rt^ characters that are 

 permanent and hereditary in bacteria is not to be 

 expected. The classification of bacteria proposed by 

 Fischer has much to commend it, but it is natural to 

 shrink from so sweeping a change in our existing nomen- 

 clature as would be necessary if his views were 

 universally adopted. The tetanus bacillus, according to 

 Fischer, would fall under the genus Plectridium, the sub- 

 family Plectridiaj, the family Bacillaceae, and the order 

 Haplobacterin?e. The typhoid bacillus would come 

 under the same order, but the genus would be Bactridium, 

 the sub-family Bacilleac, and the family Bacillaceas. 



Fischer suggests that 

 "the names of the genera might be formed conveniently 

 in such a way that the root of the word indicated the 

 shape of the cell, and the termination the arrangement 

 of the cilia. The root-words might be baktron (rod), 

 kloster (spindle), and plectroti (drum-stick), and the 

 terminations -inium for monotrichous, -ilium for lopto- 

 trichous, and -idium for peritrichous types." 



Chapter v. deals with the distribution of bacteria ; their 

 modes of life, and spontaneous generation. Using the 

 modes of nutrition as a basis for classification, Fischer 

 divides bacteria into the following groups : — 



I. Prototrophic Bacteria. 



Nitrifying bacteria, bacteria of root-nodules, sulphur 

 and iron bacteria, occur only in the open in nature — 

 never parasitic, always monotrophic. 



II. Metatrophic Bacteria. 

 Zymogenic, saprogenic and saphrophile bacteria 



occur in the open and upon the external and internal 

 surfaces of the body — sometimes parasitic (facultative 

 parasites), monotrophic or polytrophic. 



NO. 161 I, VOL. 62] 



III. Paratrophic Bacteria. 



Occur only in the tissues and vessels of living 

 organisms — true (obligatory) parasites. 



The author remarks that it is worthy of note that not 

 only the bacteria but all other organisms can be arranged 

 in these three biological divisions. 



Chapters vi. to ix. deal with thephysiology of nutrition, 

 general principles of culture, respiration of bacteria, 

 influence of physical agents, and the action of chemicals. 

 It is impossible in the limits of this review to do justice 

 to these chapters, which although treating of matters 

 described in every text-book of bacteriology, yet succeed 

 in presenting the subject to the reader in a new and 

 attractive light. 



Chapters x. and xi. treat of the circulation of nitrogen 

 in nature. It may be said without fear of contradiction 

 that the author has dealt with this complex problem in a 

 masterly manner. No other writer that we are aware of 

 (unless, perhaps, Lafar) has placed the subject before the 

 reader in so comprehensive and intelligible a form. To 

 indicate the scope of these chapters we cannot forbear 

 quoting from the introductory remarks as follows :— 



"Apart from the activity of organisms like the pig- 

 ment and phosphorescent bacteria, and other remarkable 

 metabolism of the sulphur — and iron — bacteria, the work 

 of bacteria in nature embraces three great processes : 



(i) The circulation of nitrogen: effected by putre- 

 faction, the formation of nitrates, and the assimilation of 

 atmospheric nitrogen. 



(2) The circulation of carbon by the fermentation of 

 carbohydrates and other non nitrogenous products of 

 animals and plants. 



(3) The causation of disease in other organisms, 

 particularly in man and the higher animals. 



There are in nature five sources of nitrogen open to 

 plants and animals : 



(i) The atmosphere (79 per cent, by volume of free 

 nitrogen). 



(2) The nitrates of the soil and the traces of nitrous 

 acid formed in the air during thunderstorms. 



(3) Ammonia, which occurs in minute quantities in the 

 air, and is set free abundantly by the putrefaction and 

 decay of dead organisms. 



(4) Animal excreta, which contains nitrogen compounds 

 of many kinds, even down to ammonia ; and 



(5) The tissue of plants and animals." 



Chapters xii. to xiv. deal with the circulation of carbon 

 dioxide in nature, and they are full of interest to the 

 biologist, and will doubtless appeal very strongly to 

 students of agricultural chemistry. 



Chapters xv. to xvii. treat of bacteria in relation to 

 disease. In no captious spirit we venture to offer the 

 criticism that here the author treads on less familiar 

 ground, and although the subject is discussed in a 

 scholarly and instructive manner, there is some evidence 

 that a pure botanist is apt to fall into error when invading 

 the domain of the pathologist. We do not agree with 

 the author when he says that B. coli is almost indistin- 

 guishable from the parasite of typhoid fever. It is 

 easily distinguished — the difficulty lies in differentiating 

 between certain phase-forms or allies of B. coli and the 

 typhoid germ. Again, Prof. Fischer would seem to be 

 in error when he says that the dimensions of the two are 

 about the same, that both are actively motile and 

 peritrichously ciliated, and that the cilia are too delicate 

 for their number to be of determinative value. As a 



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