340 GENERAL SYSTEMATIC BACTERIOLOGY 



Bergey et al. (1923, p. 241) include this as the single genus of the 

 tribe Lactohacillae. 



Lactobacter. A name applied by Beijerinck (1900, p. 200) to include 

 all lactic acid bacteria, both rods and cocci. It may be regarded as 

 a physiological genus. It has been used only as a casual name. It is 

 rejected by Erwin F. Smith (1905). 



Lactobacteriaceae. A family name proposed by Orla-Jensen (1921, 

 p. 271) in the following statement: 



Although it is well-known that the rod as well as the colorless sulphur bacteria 

 may appear in all the forms known in the world of bacteria, and that even a single 

 species of bacteria (for instance, Crenoihrix and Azotobacter) in the first state 

 of development may only divide in one plane but later in more planes, yet the 

 Committee cannot admit that in case of other bacteria there may be a near re- 

 lationship between sphere-, rod- and screw-forms. Still I entertain a perhaps not 

 unwarranted hope, that my recently published monograph of the lactic acid 

 bacteria may be able to change the opinion of the Committee. Here we have to do 

 with a large group of bacteria consisting of sphere- as well as rod-forms, never- 

 theless forming a natural family which we could call Lactobacteriaceae. This 

 family I have founded, of course, not only on the specially developed power of 

 forming lactic acid (since there exist many different organisms which are able to 

 form, at any rate, small quantities of lactic acid) ; but I base it upon the fact 

 that the bacteria which we call true lactic acid bacteria have so many other 

 properties in common that there cannot be any doubt about their close relation- 

 ship. Thus, they are Gram-positive, facultatively anaerobic (without surface 

 growth in stab culture), they make excessively great demands as to nitrogenous 

 nutriment, and, most remarkably, in contradistinction to most other bacteria, 

 the}'' are unable to liberate oxygen from peroxide of hydrogen. 



Lactococcus. A genus proposed by Beijerinck (1901, p. 213). He 

 emphasizes that this genus and Lactobacillus are natural genera. He 

 states: 



Les ferments actifs (lactique) appartiennent a deux genera naturels, Lacto- 

 bacillus et Lactococcus, qui se distinguent nettement aussi bien par la forme que 

 par leurs qualities physiologiques et qui, d'apres ma conception sont certainement 

 des genres phylogenetiques et non point des genres physiologiques, comme par 

 example Photobacter, ou simplement morphologique comme les genres Bacillus, 

 Pseudomonas, Micrococcus, etc., qui tous contiennent des formes bien e'loign^es 

 dans le syst^me naturel. 



The genus includes those cocci, both diplococci and streptococci 

 which at temperatures below 30°C. produce the lactic fermentation of 

 milk, and which commonly produce dextrorotatory lactic acid. The 

 most common species, the form which may be regarded as the type, 

 is Lactococcus lactis, the Bacterium lactis acidi of Leichmann (1896, p. 



