158 



80 



frequently be met with in condensed milk^) and other extracts concentrated in vacuum 

 (Nos. 15. 23. 24 and 2). 



As seen from Table XXVII, the less aerobic, as also the mycoderma-like tetracocci 

 form dextro-lactic acid, whereas the lactic acid in Aureus- and Albus-iovms. as far as thev 

 produce any noticeable quantity at all. is inactive or lævorotatorj-. The bv-products are as 

 a rule acetic acid. Those bacteria which formed too small a quantity of lactic acid for iden- 

 tification will possibly burn a part of the sugar entirely, to carbonic acid and water. Thev 

 are, at any rate, like so many other aerobic organisms, capable of burning a quantitv 

 of organic acids, as for instance that formed by sterilisation of the sugars, and the degree 

 of acidity will therefore often decrease gradually in cultures with sugars which are not 

 fermented; this is indicated in the tables by ~. The decomposition of proteins, however, 

 also contributed in some degree to this diminution of the acid. 



As the limit between slight fermentation of sugar and none at all is somewhat vague 

 in the case of the tetracocci. the relation of these bacteria to the different sugars has not 

 quite the same value as in the case of the other lactic acid bacteria. Some points are. 

 however, fairly characteristic. The two least aerobic strains, for instance (Nos. 1 and 2), 

 ferment arabinose, mannite and salicin, whereas the two mastitis bacteria (Xos. 3 and 4) 

 do not ferment any of these sugars. Xos. 5, 6 and 7, which do not liquefy gelatin, have all 

 three shown a decrease, in the course of years, of their power to ferment xylose, but all 

 still ferment arabinose, raffinose and salicin. Xos. 9. 10 and 11, which are powerful liquefiers of 

 gelatin, do not. on the other hand, ferment the mentioned sugars to any considerable degree. 

 The typical Albus-lorms (Nos. 28 and 29) are distinguished from the typical Aureus- 

 forms (Xos. 13 and 14) by fermenting sorbite, and often also pentoses, raffinose and 

 salicin. The mycoderma forms (Xos. 30 and 31) likexsise ferment pentoses and sorbite, 

 and have a relatively high fermentation of glycerin. They therefore thrive well on the sur- 

 face of cheese where a splitting up of fat takes place. 



As regards the morphology of the tetracocci, we have Little to add to what has alrea- 

 dy been said. Of the strains investigated by us, only Xo. 8 (PI. XXVII) appeared through- 

 out unaltered as a typical sarcina in all respects. And in accordance with this, it has a 

 knotty, or at tunes even mesenteric surface growth, and forms in broth compact small 

 clumps which at once sink to the bottom. Xo.3 (PI. XXVII) has, in broth, a slight tendency 

 to sarcina form. Xo. 11 (PI. XXVI), which in milk originally formed pachets. lost this 

 quality through regular re-inoculation, and then appeared as a diplococcus. After long 

 periods of rest (it could be preserved for three years in starch water without re-inocula- 

 tion), it however regained the sarcina form for a time. This feature, together with the 

 strong yellow (even at times orange or pink) markedly spreading surface growth, distin- 

 guishes Xo. 11 from the related strains Nos. 9 and 10. As 1 have pre\iously called these 

 important cheese bacteria Micrococcus casei liquefaciens-). they should, according to the 

 altered nomenclature, be called Tetracoccus casei liquefaciens: I prefer, however, simply 

 to call them Tetracoccus liquefaciens. Xos. 5. 6 and 7, which are also of frequent occurrence 

 in cheese, can reasonably be called Tetracoccus casei. No. 5 is distinguished from the two 



') We are here concerned, of course, with sugared milk; the onsugared. it need hardly be said 

 is sterilised. 



*i Ohla-Jensen, Doktordisputats 1904. 



