no NATURAL SCIENCE. Feb., 



over a period of several weeks, the horse is bled and the serum 

 collected with all possible antiseptic precautions. By careful drying 

 at a comparatively low temperature it can be stored safely without 

 any loss of its antitoxic power. 



Before use each sample of serum requires testing as to its anti- 

 toxic strength. This is done in the laboratory, and consists in 

 determining what amount is required to protect a guinea-pig against 

 a known standard fatal dose of a diphtheria culture, the result being 

 stated in terms of the amount required to protect one gramme of 

 guinea-pig. From this the dose for a child or adult human being can 

 be calculated. With the more powerful antitoxic serums this amounts 

 to about lo c.c. With the weaker serums 30 c.c. or more have to be 

 injected. 



Before forming any opinion as to the results of antitoxin treat- 

 ment in cases of human diphtheria, it is necessary to consider one or 

 two important points as to diphtheria statistics. In the first place, 

 diphtheria has not been in the past — and, perhaps, still is not — a disease 

 to be recognised with certainty. It may be confounded with other 

 exudative affections of the throat, and in its slighter forms is readily 

 passed over as simple sore throat. According to Dr. Thorne Thorne, 

 the main way in which it is spread is by means of slight and unrecog- 

 nised cases in elementary schools. Itis probable that wenow have, in the 

 presence or absence of the diphtheria bacillus, a positive criterion as to 

 the nature of any given case, and no statistics are at the present time 

 of much value unless based on bacteriological diagnosis. It follows 

 that the statistics of past years are not wholly comparable with those 

 of the present. It is to be noted also that, since only the more 

 severe and well-marked cases are, as a rule, treated in hospitals, the 

 fatality deduced from hospital statistics will be relatively too high. 

 Further, the fatality of diphtheria varies very widely in different 

 epidemics and in different years, so that statistics of one year are not 

 necessarily comparable with those of another. The most reliable 

 results will be attained by comparing the statistics of cases treated 

 with and without antitoxin during a given epidemic. Since accurate 

 bacteriological diagnosis is rarely practicable except in hospitals, 

 hospital statistics are those that have the most value, and it is plain 

 that the value of a new treatment, if it have any, will be most 

 apparent among the severer cases which come into hospitals. 

 Statistics of tracheotomy cases will have a special importance from 

 this point of view, for these are the most severe and dangerous cases 

 ■■ of diphtheria that have to be dealt with. 



Diphtheria is a disease which has of late years shown a con- 

 siderable increase in urban districts, though there is no evidence that 

 its fatality has increased. In London, the statistics of the Metro- 

 politan Asylums Board Hospitals show a fatality^ which has fallen 

 from 46-4 per cent, in 1888, when diphtheria was first admitted into 



^Fatality means case-mortality. 



