Nellie B. Eales 31 



(2) How do new cheeses become infected in a cheese room pre- 

 viously attacked? 



The second question may be more conveniently dealt with first 

 and its solution involves to a large extent the answer to the first question. 

 Stiltons are usually made from April to September, and are then 

 cleared out of the dairies by December. From December till the end 

 of April, that is to say, till the next Stilton season, the Stilton room 

 is usually empty or is used for other cheeses which are not attacked by 

 mites unless very old. From such a cheese room, which had been 

 used since Christmas only for cheeses that are not usually attacked, 

 scrapings from corners, window ledges and shelves were taken in June. 

 In each case, amongst a mass of dust and dead bodies of mites, a few 

 live mites were found. The new Stiltons were placed on the shelves 

 at the end of June and in a fortnight's time showed numbers of mites 

 on the coat. The mites that attacked the new Stiltons, therefore, were 

 already present in the cheese room. The ordinary cleansing methods 

 had failed to kill them, yet the greatest care is taken in this dairy to 

 keep the place thoroughly clean. Eggs were never seen in the scrapings ; 

 all the individuals were adults, and it appears probable that the interval 

 between the Stilton periods is tided over by adults. Now if these 

 few adults are the source of mite attack on the new Stiltons, how do 

 they spread from cheese to cheese and from shelf to shelf ? It is obvious 

 that on emerging from their retreats they will crawl to the nearest 

 cheeses, but this does not entirely explain how thej pass from one 

 shelf to another. Two experiments were carried out in order to ascer- 

 tain this. In both these experiments the crawling of the mites to the 

 cheese was prevented by a band of grease in the one case and by a water 

 bath in the other. 



Eocperiment 1. A trestle stool, which had never been used in the 

 cheese room, was thoroughly scrubbed and placed in the centre of the 

 Stilton room. The legs were thickly smeared with vaseline about six 

 inches from the floor. Any mites, therefore, that attempted to crawl 

 up from the floor would be caught by the grease band. A sheet of 

 plate glass was placed on the trestle and on it four new Stiltons. These 

 cheeses were turned each day by the same student, who did not touch 

 any of the mite attacked cheeses, so that it was improbable that she 

 could carry mites to these four cheeses. Since the mites could not 

 crawl on to the cheeses, and these were nevertheless attacked about two 

 weeks later than the other Stiltons in the room, there were three 

 possibilities : 



