The sarcina is a micrococcus which in dividing shows lines of fission in three directions at right angles, so that it always divides into fours. The fours often remain adherent, so that we may have groups of four, eight, sixteen, or further multiples (see Fig. 155). There are several forms of sarcinae which may appear spontaneously in various media, their source being the air, and from these pure cultivations may be obtained. The forms are distinguished by the colour of the cultures, as white, yellow, and orange.

Sarcina ventriculi (Goodsir) is a form found in the stomach, especially when the organ is greatly dilated and processes of fermentation are proceeding. It occurs as cubical packets of micrococci which frequently have a brownish colour when seen under the microscope (see Fig. 155). When cultivated on nutrient media it grows in light yellow colonies. It has no special significance in the stomach, where it occurs along with other fermentative bacteria.

Sarcinae have also been observed in other situations. If blood be taken fresh from the vessels into a capillary tube and preserved in a water-bath at a temperature near that of the body, then in almost every case sarcinae will develop in a few days (Lostorfer and Ferrier).

Fig. 155. - From vomited matter, showing (a) sarcinae ventriculi, (b) starch granules, and (c) fungus spores, x 350.

They first appear as globular glancing bodies and then form the regular cubical packets. They are smaller than those found in the stomach, but in nutrient media they grow to that size. Sarcinse have also been found in gangrenous cavities in the lungs, and in the urine, being probably derived from the blood.