coccus could be isolated from the naso-phaiiiyx of healthy persons living in epidemic zones.
In other words, they isolated the meningococcus from healthy con- tacts ; for every case of cerebro-spinal fever there exist in times of epidemic a number of healthy carriers variously estimated at from ten to thirty.
The number of contacts varies with several inconstant factors : — 1. There is a seasonal incidence for carriers as there is for cases ; there are twice as many carriers in the spring months as in the summer months. 2. The number of carriers varies also with the stage, and with the character of the epidemic ; there are more carriers when the epidemic is fully developed than during the waxing and waning stages, and there are also more carriers when the epidemic is severe than when it is mild. 3. The closeness of contact between the individuals affects the number of carriers : mothers who nurse their meningotic infants are found to be carriers almost invariably, and carriers are particularly abundant in schools and barracks.
The conditions under which the meningococcus is carried in the throat are very snnilar to those of diphtheria carriers where also the organisms' stay in the throat may be temporary or prolonged.
In diphtheria the organism may exist in some for years.
The limit with the meningococcus as far as it is at present known is six months. Surgeon-Colonel Eeece tells me of one case in which it has lasted for a year, and another case, like " Charley's Aunt," is still running.
A temporary carrier is comparatively easy to deal with. The organism seldom survives for as long as a fortnight in the throat ; contacts giving two negative results may be discharged to duty.
In a number of cases the first swab is positive, while the second swab, taken some ten days later, and all subsequent swabs, proved negative. The period of isolation required in such a case is, therefore, short.
Prolonged carriers are very much more difficult to deal with, as it is hardly practicable even in the case of troops to isolate an individual for
