6j4 



NA TURE 



[October 27, 1892 



number of experiments on the relative value of various 

 disinfectants and disinfectant processes. Since the 

 introduction of Koch's methods, the study of the 

 subject of disinfection has been immensely assisted, 

 and it is now possible to take a more accurate measure of 

 the extent to which micro-organisms are affected by 

 different treatment, whether chemical or mechanical. 

 The stimulus which it has thus received has not un- 

 naturally drawn a large number of workers into this par- 

 ticular field of inquiry, and the literature is already very 

 unwieldy. 



One of the principal difficulties which surround the 

 study of micro-organisms is their individuality, their 

 apparent idiosyncrasies, and this is not confined to closely 

 allied varieties, but is found amongst members of one 

 and the same species. Thus, the previous history of a 

 micro-organism, the nature of the culture material used, 

 the temperature at which the cultivation has been kept, 

 the age of the growth, &c., are all points which have to 

 be taken into consideration as likely to influence the be- 

 haviour of the particular specimen under observation. 

 This sensitiveness- of bacteria may possibly to some 

 extent account for the discrepant results which have been 

 obtained by different investigators, although working in 

 similar directions, which has rendered the accurate ap- 

 preciation of the value of these results a by no means 

 easy task. Again, what succeeds in a laboratory is not 

 necessarily equally successful when carried ouc on a large 

 scale, and it is this difficulty which has so frequently led 

 to such disappointing results in actual practice. 



Prof. Maschek has endeavoured by a series of most 

 arduous and painstaking experiments to throw a little more 

 light on some of the problems of disinfection, and in 

 gathering up his work has wisely abstained from attempt- 

 ing an exhaustive survey of the general literature, re- 

 stricting himself to a brief introduction and particular 

 reference to those investigations with which he has been 

 more closely concerned. In the majority of the experi- 

 ments the author employed Koch's well-known method 

 of sterilized silk threads, each of which was subsequently 

 impregnated with pure cultivations of a number ot differ- 

 ent pathogenic micro-organisms. These were distributed 

 in various parts of a room about 19-ft. long, 13-ft. wide, 

 and 154-ft. high, on the ceiling, walls, corners, floor, &c., 

 whilst in some cases they were wrapped up in differ- 

 ent materials, such as filter-paper, muslin, linen, in 

 order to imitate as nearly as possible the actual condi- 

 tions under which the organisms might be supposed to 

 be present in an infected room. In each case, after 

 the application of the disinfectants under observation, 

 these silk threads were submitted to plate-cultivation, 

 and in some instances their pathogenic properties were 

 also tested by inoculation into animals. 



The first elaborate series of experiments was made 

 with the vapour of corrosive sublimate, which some 

 authorities have recommended as an effective germicidal 

 agent ; but quite apart from the difficulty of getting rid of 

 the poisonous crystals of corrosive sublimate which 

 remained attached to various parts of the room, Prof. 

 Maschek was not able to obtain satisfactory results, 

 although every precaution was taken to ensure success. 

 In this respect his experiments differ from those of Konig, 

 who confidently recommended its use for disinfection 

 purposes. The effect of chlorine gas was next tested and 

 applied both in the dry and damp state. The results 

 were, however, far from encouraging, for even when 

 employed in the damp state the spores were not de- 

 stroyed. In connection with these experiments a very 

 instructive instance is givan of the signal failure which 

 accompanied the use of chlorine in the Alexander Hos- 

 pital in St. Petersburg, which was designed for receiving 

 different infectious illnesses. Suspicion as to its efficacy 

 was first aroused after its use in the disinfection of a 

 ward in which diphtheria pitients had been treated. 



NO. 1200, VOL. 46] 



This ward was afterwards used for scarlet fever cases, 

 and subsequently complications with dipht .eria made 

 their appearance, in consequence of which the ward was 

 closed and disinfected with chlorine. (A ward of 900 

 cubic metres capacity being subjected to the chlorine gas 

 evolved in treating 50 kilos, of chloride of lime with 65 

 kilos, of hydrochloric acid.) After the disinfection was 

 completed, the ward was thoroughly cleansed and venti- 

 lated, and allowed to remain empty for seven months. 

 On its being re-opened for the reception of measles cases 

 complications with diphtheria again arose, although the 

 patients when taken into the ward were wholly free from 

 diphtheria. The measles patients were therefore re- 

 moved, and the ward was again disinfected with chlorine, 

 only this time a much larger quantity'was employed (135 

 kilos, of chloride of lime with 1485 kilos, of hydrochloric 

 acid) after which it stood empty for another seven 

 months. Later on cases of smallpox were received into 

 this ward, but diphtheria again appeared, the physician, 

 two nurses, and an attendant being amongst those 

 attacked, whilst complications with diphtheria again 

 occurred amongst the patients. In consequence of this 

 the unfortunate ward was once more closed and thoroughly 

 disinfected with chlorine, and was reopened for typhoid 

 fever patients ; but all children's cases were rigorously 

 excluded, in consequence of their particular susceptibility 

 to diphtheria. After the adoption of this special precau- 

 tion no further attacks of diphtheria were met with. It 

 might, however, be urged that as regards the infection of 

 patients suffering from measles with diphtheria, the 

 disease was possibly introduced from outside, and did not 

 necessarily arise in the ward itself, were it not for the fact 

 that there were three other wards in the hospital in which 

 cases of measles were being treated at the same time, and 

 no single attack of diphtheria occurred. Krupin, who is 

 the authority for these facts, confirmingthe valuelessness of 

 chlorine for disinfecting purposes, found that the spores 

 of anthrax were not destroyed in a hospital ward after 

 being exposed to the action of this gas for more than 40 

 hours. 



A large number of experiments were made with a 

 view to determining the number of micro-organisms 

 present on the walls of a room. For this purpose a small 

 sterilized bit of sponge cut in the shape of a cube (of 

 about half-inch side) was used to rub down a measured 

 portion (about 4 square inches) of the wall. The sponge 

 was afterwards placed in a tube containing sterile melted 

 gelatine and rotated gently, so as to disengage all the 

 organisms on its surface. The gelatine was then allowed 

 to congeal on the sides of the tube, and after suitable 

 incubation the colonies made their appearance, and were 

 estimated in due course. It was found that the numbers 

 present on the walls and ceiling respectively varied con- 

 siderably. Near the floor the number was much greater 

 than on the middle of the wall, whilst here again they 

 were more abundant than on the ceiling. For example, 

 on one of the walls, at a distance of rather more than 

 an inch from the ground, as many as 2,871 microbes were 

 found, whilst on the ceiling over a similar area only 85 

 were discovered. It was also noticed that those portions 

 of the wall or ceiling which were exposed to currents of 

 air from either the window or door exhibited generally a 

 smaller number of bacteria than did places which were 

 shielded from such draughts. Prof. Maschek further 

 found that one rubbing was wholly insufficient to remove 

 all the organisms from a given surface, and it was only 

 after the process had been repeated five times that all 

 bacterial life could be banished with certainty. Although 

 the figures thus obtained are of interest by way of com- 

 parison, yet it is difficult to believe that they represent 

 the actual numbers present. The accuracy of this method, 

 originally devised by Esmarch, rests on the assump- 

 tion that on placing the sponge in the tube of melted 

 gelatine and rotating it gently (for if this were done 



