Sanitation 595 



Knorr, Yersin, Calmette, and Borrel* have shown that 

 the bacillus made virulent by frequent passage through mice 

 is not increased in virulence for rabbits. 



This no doubt depends upon the sensitivity of the bacillus 

 to the protective substances of the body juices, immuniza- 

 tion against those of one animal not necessarily protecting 

 the organism against those of other animals. 



Bielonovskyf finds that broth, agar, and serum cultures 

 of the plague bacillus possess the property of hemolyzing 

 the blood of normal animals. The hemolytic power of fil- 

 trates of plague cultures increases up to the thirteenth or 

 fourteenth day, then gradually diminishes, but without 

 completely disappearing. The hemolysins are notably re- 

 sistant to heat, not being destroyed below 100 C. 



Sanitation. A disease that may be transmitted from 

 man to man by atmospheric infection and inhalation, that can 

 be transported from place to place by fomites, that occurs in 

 epidemic form among the lower animals as well as among men, 

 and that can be transmitted from man to man and from lower 

 animals to man by biting insects, must inevitably become a 

 source of anxiety to the sanitarian. 



The preventive measures must take account of men, rats, 

 and goods. If vessels are permitted to visit and leave plague- 

 stricken ports, means must be taken to see that all passengers 

 are healthy at the time of leaving and have remained so 

 during the voyage, and provision should be made at the port 

 of entry for the disinfection of the cargo before the foods are 

 landed. But the rats must be given special consideration, 

 for so soon as the vessel reaches port some of them jump over- 

 board and swim to the shore, carrying the disease with them. 

 When a vessel visits a plague port, every precaution should be 

 taken to orevent the entrance of rats, first by anchoring 

 in the stream instead of tying to the dock ; by carefully scru- 

 tinizing the packages taken from the lighters to see that there 

 are no rats hidden among them ; by placing large metal shields 

 or reversed funnels about all anchor chains, hawsers, and 

 cables so that no rats can climb up from the water in which 

 they are swimming at night. Arrangements should also be 

 made for rat destruction on board the ship by means of sul- 

 phurous oxid or other poisonous vapors to rid the ship of 

 rats before the next port is reached. Passengers and crew 



* "Ann. de 1'Inst. Pasteur.," July, 1895. 



t "Arch, des Sci. Biol.," Tome x, No. 4, St. Petersb., 1904. 



