For identification of a new microbe it is necessary to compare its behavior with that of standard types, hence 

 the nerd of a collection of standard type^. Each pin on the map above represents a university, or normal-school, 

 or board-of-health laboratory which has received cultures for study from the American Museum collection 



by totu'hing the old growth with the tip 

 of a platinum needle and transferring an 

 invisible, but potent, inoculum to a new 

 culture tube. 



There are now about seven hundred 

 different strains of living t)acteria in the 

 Museum collection, representing practi- 

 cally all known types of this di\'erse 

 group. Bul)onic plague has alone been 

 excluded, on account of accidents which 

 have occurred in other laboratories with 

 this peculiarly deadly germ. Typhoid 

 and diphtheria germs, however, are to 

 be found, with those of whooping cough 

 and cholera, meningitis and leprosy, 

 influenza and pneiuuonia, and a dozen 

 more of such pathogenic forms. The 

 original strain of tubercle bacillus iso- 

 lated by Robert Koch is there, with one 

 of the most recently discovered of disease 

 germs, isolated by Plotz and believed 

 by him to be the cause of typhus fever. 

 In the collection, also, are the bacteria 



which cause plant diseases and those 

 which decompose foods. There are 

 strains of the Bulgarian bacillus which 

 makes buttermilk and the lactic acid 

 t)acteria utilized by the tanner. One 

 germ that infects sugar cane came from 

 Louisiana and another was found fixing 

 nitrogen in the soil of a bean field in 

 the Middle West. 



The keeping of records incident to the 

 maintenance of this collection is in itself 

 no light task. For each of the nearly 

 seven hundred types there is a history 

 card with a serial number on which 

 every single transfer to a fresh tube is 

 entered, with the date and the initials of 

 the bacteriologist, so that one can tell at 

 a glance exactly what has happened to 

 each strain since it was added to the 

 collection. The previous history, source, 

 and original date of isolation of the cul- 

 ture is of course kept on file, and a cross 

 index by names makes it possible to find 



297 



