Note 29 — Chapter III · On the Origin of Ferments properly so called.

We must mention one curious result, which relates to what have been called the crystals of the blood. We could hardly have recourse to a better method of preparing these crystals, at least in the case of dog’s blood, which seems to yield them with the greatest facility in any quantity we might desire to procure. Under the circumstances just recounted, in which dog’s blood exposed to contact with pure air underwent no putrefactive change whatever, the crystals of that blood formed with a remarkable rapidity. From the first day that it was placed in the oven and exposed to an ordinary temperature, the serum began gradually to assume a dark brown hue. In proportion as this effect was produced, the globules of blood disappeared, and the serum and the coagulum became filled with very distinct crystals, of a brown or red colour. In the course of a few weeks, not a single globule of blood remained, either in the serum or coagulum; every drop of serum contained thousands of these crystals, and the smallest particle of coagulum, when bruised under a piece of glass, presented to view colourless and very elastic fibrine, associated with masses of crystals, without the slightest trace of blood-globules. Where our observations were protracted, it sometimes happened that all the fibrine collected into one hyaline mass, which gradually expelled every crystal from its interior.