The history of bacteriology / by William Bulloch.

  • Bulloch, William, 1868-1941.
Date:
1938
Catalogue details

Licence: In copyright

Credit: The history of bacteriology / by William Bulloch. Source: Wellcome Collection.

    91/476 (page 69)
    insects. He also found ova which he considered had been dropped on the flesh by flies. He was confirmed in his belief by finding that before the flesh grew wormy, flies hovered over it of the same kind as those that later bred in it. ‘Belief’, says Redi, ‘would be in vain without the con¬ firmation of experiment.’ He therefore put a snake, some fish, some eels, and a slice of milk-fed veal into four wide¬ mouthed vessels, and having well closed them with paper tied on, he prepared similar vessels in the same way except that they were left open. In the latter series the flesh rapidly teemed with maggots but he could find none in the closed series, although here and there on the paper cover he saw maggots eagerly seeking any crevice through which they could penetrate to obtain food. As the experiments had been made with closed vessels which might have hindered the circulation of air he made other experiments in which the air might freely enter but flies could not. For this purpose he placed meat and fish in large vessels closed with the finest Naples gauze (.sottilissimo veto di Napoli) and for further protection against flies he placed the vessels in a frame covered with the same gauze. Many flies were found moving about on the frame but no maggots appeared in the meat. On occasions he saw the flies deposit their ova on the net or even in the air before they reached the net. By such experiments Redi destroyed for ever the myth that maggots are bred spontaneously from meat. In other experiments he traced the development of the ova through maggots to fully formed flies of divers sorts. Redi described himself as the most incredulous man in the world (incredulo uomo del mondo) with regard to natural phenomena, and admitted that in bygone days when blinded by inexperience he believed in things ‘which I am now ashamed to re¬ member’. He studied worms in all sorts of vegetation and, strange to say, he ultimately concluded that fruits, vege¬ tables, trees, and leaves show grubs in two ways. In the one they come from without and gnaw a path inward, whereas in the other he thought that spontaneous genera¬ tion was possible and that the soul or principle which