S4 



NATURE 



[May 25, 1893 





the typical aspect, i.e. uniform threads and chains of rod* 

 shaped elements. 



Another photograph which I show you here is from a colony 

 of the bacillus of diphtheria. Here also you notice the appear- 

 ances already mentioned of the anthrax bacilli, viz. shorter or 

 longer filaments, in which some of the elements show a con- 

 spicuous enlargement : pear-shaped, spherical, or club-shaped. 

 Such forms are not involution forms : they occur in vigorous 

 and actively growing young colonies. 



A still further -illustration, and one of great importance, is 

 shown by this photograph, illustrating a similar change of the 

 tubercle bacilli. This change has now been confirmed by several 

 independent observers. The typical tubercle bacilli of human 

 or bovine tubercle and of early cultivations are cylindrical 

 rods. In cultivations of long duration but still actively grow- 

 ing you notice forms which .ire more filamentous, and, as in the 

 present illustrations, are branched filaments with club-shaped 

 enlargements. 



From all this the conclusion is justified that in all these cases 

 of bacilli the typical cylindrical bacilli show occasionally an 

 indication that reminds one of forms belonging to the higher 

 or mycelial fungi, in which the growing filaments remain un- 

 segmented and become thickened and even branched. These 

 thickened, branched, and club-shaped forms of the bacilli 

 would correspond to an atavism, and would recall a probable 

 former fungoid phase in the evolutional history of these 

 bacilli. 



The next point to which I wish to call your attention 

 is the rapidity with which multiplication of the bacteria 

 takes place. This differs according to the amount and nature 

 of the nutriment or soil on which they grow, and to the tempera- 

 ture. While some bacteria multiply even at lower temperatures 

 at a great rate, others do so only at higher temperatures. But in 

 order to give you an idea of the power and the rate of multipli- 

 c.ition I may men'ion the following : — Direct observations show 

 that the rate at which bacteria divide at a temperature of 20°C. 

 varies from eighteen minutes to thirty minutes or a little longer, 

 and at higher temperatures correspondingly faster. A tube of 

 nutrient broth was inoculated with a trace of the growth of a 

 staphylococcus (Staphylococcus pyogenes aureus), the number of 

 cacci introduced into the tube having been previously determined 

 to be 8 per cubic centimetre. The tube was then kept at 37°C. ; 

 in the first twenty-four hours the cocci had multiplied to 

 640,000 per cubic centimetre ; in the second twenty-four hours 

 to 248 millions per cubic centimetre, and in the third twenty- 

 f<5ur hours to 1184 millions per cubic centimetre. . 



A point of interest is the motility exhibited by some bacteria. 

 Tn some species most, in others comparatively few, individuals 

 show active locomotion, spinning round and darting to and 

 fro ; in many other species no motility is observed. In the 

 motile species it is known that this motility is due to the 

 presence and active motion of cilia or flagella, and these have 

 been seen and photographed in former years in some of the 

 larger forms, but only within recent years has it been possible, 

 by means of new methods (Lofflir), to actually demonstrate in 

 the smallest forms these flagella, and here the remarkable facts 

 have been shown that while some possess only one flagellum at 

 one eid, in other species the bacillus possesses a bundle of 

 them, or is covered with the flagella on its whole .surface. I 

 show here some photos of the flagella, one possessing two 

 flagella at one end (spirillum volutans), the other (cholera ba- 

 cillus) one at one end, and the third (typhoid bacillus) is covered 

 with quite a number of flagella. 



A not less interesting point is the formation of spores : the only 

 trustworthily ascertained mode of spore formation is that which 

 is called endospores, as is shown in the following photograms ; 

 a bacillus at a certain phase develops in its protoplasm a minute 

 glistening granule, this increases in size and becomes oval, while 

 the rest of the substance of the bacillus becomes pale, swells up. 

 and gradually degenerates and disappears, leaving the fully 

 formed oval bright spore free. These spores are of great re- 

 sistance to temperature, chemical obnoxious substances, drying, 

 &c., so that even after long periods and various adventures, 

 when again brought under proper and suitable conditions, they 

 are capable of germinating into the bacilli. These then grow 

 and divide and continue to do so, producing new crops. Non- 

 sporing bacteria are for this reason more liable to succumb in 

 the struggle for existence, although many species of non-sporing 

 bacilli have such a vast power of multiplication and are so little 

 selective in their requirements that they milage to keep 



NO. 1230, VOL. 4^ 



their crops perpetually going ; some notorious putrefactive cocci 

 and bacilli belong to this class. Having now mentioned the 

 essential features in the morphology of bacteria, as far as is 

 possible in the limited space of time at my disposal, I proceed 

 to give you a short summary of some of the most important 

 activities which bacteria exhibit. 



Bacteria causing Decomposition of Albumen. 



Foremost in importance and vastness of result is the action 

 which certain species of bacteria have on albuminous matter, an 

 action which is termed putrefactive decomposition of albumen, 

 animal or vegetable. All organic matter when deprived of life 

 is resolved into simpler compounds, is broken up into lower 

 nitrogenous principles, like leucin, tyrosin, indol, phenol, &c., 

 of which the ultimate products are ammonia, nitrites, and 

 nitrates. The plant, it may be said in a general way, builds up 

 albuminous matter from nitrates, this albuminous matter it is 

 which forms the protoplasm of its cells, this albuminous matter 

 it is which serves as nitrogenous food for animals; these .again sup- 

 plying the food for other animals and man. In the living body 

 of these the albuminous matter becomes broken up, yielding 

 nitrogenous principles like urea and allied substances, which 

 again, after further oxidation in the soil and in water, serve to 

 supply nitrates to the plant ; but also the bodies of animals and 

 plants after death form a large stock from which by a long chain 

 of processes, induced and sustained by micro-organisms, lo.ver 

 nitrogenous compounds and ultimately ammonia aud nitrates 

 are produced, from which the living plants principally draw 

 their nitrogen. 



From this it is evident that the vegetable kingdom is depen- 

 dent for its nitrogen chiefly on processes byr which from the 

 albumen of dead organic milter, by the activity of micro- 

 organisms, in the first place lower nitrogenous principles and 

 ultimately ammonia, and in the second place, also by micro- 

 organisms nitrites and nitrates are formed. Now, the micro- 

 organisms^ which are capable of producing the first series of 

 dec3mpositions of dead albuminous matter form, so to speak, the 

 first army of attack ; it is this army which, while multiplying at 

 the expense of albumen, decomposes it, and thereby is instru- 

 mental in changing it into lower nitrogenous principles such as 

 leucin, tyrosin, indol, and ammonia. Amongst the large number 

 of species of putrefictive bacteria I will describe two only, which 

 by their great distribution may be considered as playing a very 

 important part in this decomposition of albumen. The first is 

 the species known as Proteus vulgaris, the second is the Bciculus 

 coli. 



(a) Proteus vulgaris. — -This species is the compion putrefact ive 

 organism ; it is almost invariably present in dead and decaying 

 albuminous matter ; it is the organism which in dead animals 

 and man plays the principal part in the destruction and resolution 

 of the body ; it is present in the cavity of the normal intestine ; 

 it is found in connection with effete and dead matter occurring 

 in the body in health and disease ; it has a wide distribution in 

 nature, and is present wherever organic matter happens to be in 

 a state of putrescence ; it is liable to pass from this and to be 

 transmitted to other putrescible matter by air currents, by dust, 

 by water, by human contact or otherwise, and then to set up in 

 this new organic matter the same state of putrescence. The same 

 applies to the bacillus coli, which has also a very wide dis- 

 tribution, and which is in most instances associated with putre- 

 faction and decomposition of albuminous matter ; it is a normal 

 inhabitant of the human and animal intestine, and from here 

 often passes into the soil, water, and air. 



These two species of organisms may be considered then as 

 being of great importance in the destruction and resolution of 

 putrescible matter, in short of dead albuminous matter. 



I show you here photographs of these two species as they ap- 

 pear in artificial cultures, under various forms of cultivation, and 

 under the micro-icope under a magnification of looo. Both these 

 species are motile bacilli. 



The Proteus vulgaris, as its name implies, presents itself in 

 forms so varied, that it is at first sight difficult to recognise them 

 as belonging to one and the same species : coccus forms, short 

 ovals, short and long cylinders, homogeneous long threads, and 

 even spiral forms. But by artificial cultivation by exact methods 

 they can be shown to belong to one and the same species ; and 

 it can also be shown that under particular conditions of cultivation 

 the bacillus almost invariably shows itself as cylindrical and 

 thread-like forms ; whereas under other conditions it assumes 

 the character of cocci and ovals. The photographs which I 



