“In order to resolve the highly important question of the tenacity of life of the Helminths and corresponding larval forms, I made since 1871 a very long series of experiments on the _Cysticercus cellulosæ_, which were published almost at the same time with others of the same kind, made by Dr Lewis in Calcutta. Towards the end of 1874 Mr Pellizzari, of Florence, disputed the results of the investigations which I had made known two years before, _i.e._ in 1872, and agreed with Dr Lewis, who had stated already that the _Cysticercus_ exposed to a temperature of 55° C. can be held for dead after five minutes, and also with Dr Cobbold, who thought the temperature of 60° C. quite enough to kill it. But the characters he (Mr Pellizzari) relied upon, needing the exactness and precision required to enlighten and persuade in the most important scientific questions, gave rise to a mistrust in the most scrupulous amongst the men devoted to biological pursuits and to several hygienic measures on the part of the sanitary inspectors with regard to infected pork. Therefore, my conclusions, argued from the experiments made in 1871-72, were still those followed by the most important Italian cities, and approved in principle by the superior Board of Health in 1873. I expressed doubt then about the _Cysticercus_ dying at a temperature lower than 100° C., and some person misconstrued these doubts, saying that I had contradicted myself in my work. However, as I could not assert they died at 80°--100° C., I only noticed the alteration of color and cohesion which happened in the _Cysticercus_ exposed to various degrees of temperature, to the end that I might contribute usefully to the solution of the difficult question, and concluded that ‘if we could not be sure of the _Cysticercus_ dying at 80°-100° C., it was certain at all events that they perished at 125° or 130° C.’ Not wishing to prejudice the question, I never said that they did not die at 80°--100° C., but simply stated that at this temperature we could not be certain of their death. “Now, after a large number of experiments, I have been able to ascertain with exactness the lowest degree of temperature required to kill infallibly the _Cysticercus_ and other parasites of animals. The means I made use of for this kind of investigation were Mr Schulze’s heating table, the neutral tincture of carmine, the tincture of hæmatoxylon, and breeding experiments. “My method is founded essentially-- “(_a_) On the fact that the _Cysticercus_ when it is fresh and is stretched and conveniently prepared in pure water, or in chloride of soda very much diluted, and afterwards brought gradually from the temperature of the ambient air to that of the body of higher animals and to degrees of heat still more elevated, until life is extinct, keeps moving to and fro with more or less energy throughout its body, using especially its suckers and proboscis.