Many of the ornamental processes which we admire in Venetian glass were already in use in this century, as that of mille fiori, and the beautiful kind of glass known as " vitro di trina " or lace glass.
An elaborate account of the processes of making the vitro di trina and the vasi a reticelli (Plate I., fig.
He was especially successful in making vases and circular dishes of vitro di trina; one of the latter in the Correr collection at Venice, believed to have been made in his glass-house, measures 55 centimetres (nearly 23 in.) in diameter.
The sun shining, he fixed a round glass speculum (orbem e vitro) in a window-shutter, and then closing it the images of outside objects would be seen transmitted through the aperture on to the opposite wall, or better, a white paper screen suitably placed.
Metchnikoff and Bordet subsequently devised means by which a similar change could be produced in vitro, and analysed the conditions necessary for its occurrence.
An important point with regard to the therapeutic application of an anti-bacterial serum, is that when the serum is kept in vitro the complement rapidly disappears, and accordingly the complement necessary for the production of the bactericidal action must be supplied by the blood of the patient treated.
It is quite evident that bactericidal action as tested in vitro outside the body does not correspond to the degree of immunity possessed by the animal under natural conditions.