MICROCOCCUS PRODIGIOSUS ("the microbe of miracles"; known also as the Microbe of Bleeding Hosts):

By: Joseph Jacobs, L. Errera

A microscopical organism, first mentioned in 1819 by an Italian doctor, Vincenzo Sette, who observed it on polenta, a sort of Italian maize pudding, and gave it the strange name of Zaogalactina imetropha (from ζάω = "I live"; γαλαχτινή = "gelatin"; ημαι = "I am placed upon"; τροΦή = "food"); afterward called Monas prodigiosa by Ehrenberg (1848); Micrococcus prodigiosus by Cohn (1872); and Bacillus prodigiosus by Flügge (1886). It does not belong to the Infusoria, as Ehrenberg believed, but is a short, roundish bacterium, varying from about one half to one thousandth of a millimeter in size, motile, and bearing a variable number of cilia. It multiplies by simple division and forms no spores. Its colonies emit a disagreeable trimethylamin smell and generally produce a blood-red coloring-matter (sometimes pink, sometimes brownish). Cultures of this bacterium can be observed on gelatin, milk, meat, and other articles of food, especially on boiled potatoes (Fig. 1), on bread, and on wafers (Figs. 2, 3).

Its germs, though not very common, exist here and there in atmospheric dust, and are thus capable of accidentally producing "blood-spots" on different substances. These spots were formerly interpreted as indicating the wrath of Heaven; and they gave rise to the belief in miracles of "bleeding hosts," "bleeding bread," etc. Errera witnessed (1882) the "miracle" make its appearance unexpectedly on loaves of bread on which he was cultivating a certain fungus for phytochemical study. A well-known case is the epidemic in 1843 of "blood-spots" on the bread produced in the military bake-houses of Paris. The German naturalist Ehrenberg mentions (in "Ber. der Berl. Ak. der Wiss." 1848, p. 350; 1849, p. 106) a series of similar "miracles." A very characteristic one happened near Padua, Italy, in 1819, where Sette discovered its cause in the growth of the Zaogalactina. Another was observed by Ehrenberg in Berlin in 1848. Many of these "miracles" are of interest in connection with the subject of the desecration of the sacred hosts, the Jews having often been accused of transfixing those in which the microbes had appeared (see Brussels; Host, Desecration of).

Cultures of Micrococcus Prodigiosus on (1) Potato and on (2 and 3) Wafers.

It may be assumed that many of the stories of blood-miracles had no material basis, and were mere inventions; but as the Micrococcus prodigiosus grows quite easily on wafers, it is not unlikely that some accusations had their origin in the actual appearance of red spots on sacred hosts which had been kept damp and become exposed to atmospheric dust. Besides, other bacteria produce similar red spots, e.g., Bacillus kiliensis Migula, B. plymouthensis Migula, B. ruber Cohn, and Sarcina rubra Menge; and other lower organisms, e.g., Saccharomyces glutinis, on starch, potatoes, and bread; Euglena sanguinea, on standing waters, etc. Again, in other cases, red dust from ferruginous soils and precipitated by a shower may have produced so-called "blood-rain" or "blood-stains."

Nor must it be forgotten that the Christian belief in transubstantiation lent special force to any superstition which associated the idea of blood with that of the sacred host. It is reported that this belief, which was at first much contested, became general only after the "miracle" of 1264 at Bolsena. A priest who doubted the real presence of Christ in the bread of communion suddenly saw "drops of blood" falling on his linen garment. This was considered a decisive proof; and Pope Urban IV. immediately ordered the event to be solemnized by the institution of Corpus Christi Day.

It is possible also, according to a passage of Lucian quoted by Ferdinand Cohn, that the Pythagorean prohibition against eating beans was due to the fact that bloodlike spots had been observed on cooked beans which had been preserved for some time. Perhaps the Jewish custom of placing some iron in contact with every dish, on four days of the year, in order to prevent the fall of blood, supposed to drop from heaven into the food (Teḳufah Drops), may also have originated in some such case of accidental blood-red spots.