and Laboratory Methods. 1877 



is then an easy matter to take so many drops as are equal to a corresponding 

 fraction of a c. c. By this method, the use of sterile pipettes is avoided, while 

 the error is by no means greater than that occasioned by the use of several 

 pipettes and dilutions. A. Robin. 



Delaware State Board of Health Laboratory. 



A System of Recording Cultures of Bacteria Genealogically for 



Laboratory Purposes. 



The system here given furnishes a convenient means of recording all data 

 relating to the study of individual laboratory cultures of bacteria. It was devised 

 originally for stock cultures. As it served its purpose in that field very satis- 

 factorily, it has been elaborated from time to time to meet further needs until it 

 has reached its present form. 



Consideration has been given to the system published by Pease ^ and used 

 by him in his researches on cancer. In his system, both letters and figures are 

 used to designate sub-cultures, the letters alternating with the figures, double 

 letters, as AB, BC, being used when the alphabet is exhausted. In the writer's 

 system, which is an adaptation of the Dewey Decimal system of classification,'- 

 figures alone are used, the method of use being such as is easily remembered. 

 The following is the writer's system : 



Every species of bacteria, upon becoming a member of the laboratory stock, 

 is given a number in the hundreds. Thus : 



B. coli cotiwiunis, . . . 100 B. mallei, .... 400 



B. typhi abdominalis, . . 200 B. prodigiosus, . . 500 



B. diphtheria, .... 300 B. pestis buboniccE, . 600 



Individual specimens of any one species coming from different sources, are 



numbered in the order of their isolation or reception with the units from 1 to 49. 



Thus : 



B. mallei from one horse, 401 



B. mallei from a second horse, 402 



B. mallei from a different lesion in the second horse, 403 

 B. mallei from same lesion at a different time, . 404 



B. mallei from a third horse, 405 



The first culture of B. mallei isolated would be 401.1. 



A sub- (or daughter'^) culture from this original culture would be 401.11. 



A sub- (or daughter) culture from this second culture would be 401.111, and 



1 Transac. A. P. H. A., Minneapolis, 1899. 



2 Decimal Classification and Relative Index. M. Dewey. 



■^ For the sake of convenience and clearness, the following terms have been adopted in this 

 article : 



Mother culture-. — The culture from which another culture is inoculated. 

 Dau,i;hter culture. — The sub-culture from the mother culture. 

 Sister cultures. — Two or more cultures made from the same mother culture. 

 (Obviously the terms are relative. It is evident that any one culture may be a mother, a 

 daughter, and a sister culture at the same time.) 



