http://en.wikipedia.org/wiki/Eucharistic_miracleThe following is from wikipedia about the most famous Eucharistic miracle of the Catholic Church:
In the city of Lanciano, Italy, around A.D. 700, a Basilian monk and priest was assigned to celebrate the Eucharistic sacrifice in the Latin Rite in the small Church of St.Legontian. Usually celebrating in the Greek Rite and using leavened bread and having been taught that unleavened bread was invalid matter for the Holy Sacrifice he was disturbed to be constrained to use unleavened bread and had trouble believing that the miracle of transubstantiation would take place with unleavened bread. During the Mass, when he said the words of consecration (This is my Body...This is my Blood), he saw the bread change into live flesh and the wine change into live blood, which coagulated into five globules, irregular and differing in shape and size (this number corresponds to the number of wounds Christ suffered on the cross: one in each hand and foot from the nails, and the wound from the centurion's spear). He was frightened and confused by the miracle, and stood a while as if in divine ecstasy, but eventually he turned his face to the congregation, and said "Behold the Flesh and the Blood of our Most Beloved Christ." At those words, the congregation members ran to the altar and began to cry for mercy.
Various ecclesiastical investigations have been conducted upon the miracle since 1574, and the evidence of the miracle remains in Lanciano to this day. In 1970-71, Professor Odoardo Linoli, eminent Professor in Anatomy and Pathological Histology and in Chemistry and Clinical Microscopy, and Professor Ruggero Bertelli of the University of Siena, conducted a scientific investigation into the miracle. The report was published in Quaderni Sclavo di Diagnostica Clinica e di Laboratori in 1971, and reaffirmed by a scientific commission appointed by the Higher Council of the World Health Organization in 1973.<1> The following conclusions were drawn:<2>
The Flesh of the miracle is real Flesh and the Blood is real Blood.
The Flesh and the Blood belong to the human species.
The Flesh consists of the muscular tissue of the heart, which would be highly unlikely to "fake", given that only an expert hand could have done it, and not without serious difficulties.
In the Flesh we see present in section: the myocardium, the endocardium, the vagus nerve and also the left ventricle of the heart for the large thickness of the myocardium. The Flesh is a heart complete in its essential structure.
The Flesh and the Blood have the same blood type, AB, which is also the same blood type found on the Shroud of Turin and all other Eucharistic Miracles.
In the Blood there were found proteins in the same normal proportions (percentage-wise) as are found in the sero-proteic make-up of the fresh normal blood.
In the Blood there were also found these minerals: chlorides, phosphorus, magnesium, potassium, sodium and calcium.
There is no trace whatsoever of any materials or agents used to preserve the Flesh or Blood.
The Flesh and Blood of the miracle can still be seen today. The Host-Flesh, which is the same size as the large Host used today in the Latin Church, is fibrous and light brown in colour, and becomes rose-coloured when lighted from the back. The Blood consists of five coagulated globules and has an earthly colour resembling the yellow of ochre.