PART III.] Exact Amount of Heat required to kill the Cysticercus. 501 



manifested unless tlie slide be slightly warmed or irritants applied to the substance 

 of the cyst, whilst others, on the other hand, although in no way differing in 

 appearance from those just mentioned, cannot be made to manifest the slightest 

 indications of life, being in reality dead. It was therefore soon found whilst 

 experimenting on the effects of temperature, that actual destruction of the substance 

 of the cysticercus or even perceptible alteration in its appearance was not necessary 

 to bring about its death, whereas the non-manifestation of movements did not prove 

 that life was extinct. 



In order, therefore, to decide this point satisfactorily, it was considered that 

 electricity might be advantageously resorted to, in addition to ordinary irritants, 

 seeing that as long as muscular tissue preserves its vitality, a current passed through 

 it will cause it to contract. The wires from a battery were consequently attached to 

 the stage of the microscope and " induced currents " transmitted through the substance 

 of the bladder-worm under observation.* 



The first step taken was to ascertain the temperature to which meat is exposed 

 in the ordinary methods of cooking. Pieces of ordinary meat weighing from four 

 ounces to several pounds were selected, and immediately on removal from the source 

 of heat the bulb of a thermometer was introduced into its substance at various 

 stages during the process of cooking. 



The temperature of portions of beef removed from a boiler of beef-tea in which 

 they had been immersed and kept at 212° for over an hour varied from 190° to 

 200° Fht. 



The temperature of legs of mutton which had been put into the boiler almost as 

 soon as the water was put into it, averaged 140° in the interior at the moment the 

 water had reached the boiling point (212° F.), and after boiling for five minutes the 

 temperature had reached 170°. Chops and steaks before being considered well done 

 are exposed to a temperature of from 170° to 180°; at 150° they are considerably 

 underdone, the red colouring matter has not disappeared, nor does it disappear until 

 the meat has been subjected to about 10° more heat. 



In no instance did 1 observe that the cook had served meat the temperature 

 of which, when tested with the thermometer, did not exceed 150° F. At a lower 

 temperature than this the meat appeared raw, and would in all probability have 

 been returned to him. 



The next point to be ascertained was the amount of heat these entozoa would 

 resist when placed in pure water, in salt and water, or without the addition of water. 

 After satisfying myself that the samples under observation were alive, a dozen or two 

 were picked out of the affected meat, leaving a little of the latter attached, so as not 



* Should these or like experiments be repeated by others, it may be well to draw attention to the fact that, 

 if the conducting wires are accidentally permitted to touch the brass work of the microscope, an extremely painful 

 shock may be received by the eye of the observer, which might, as occurred to myself, necessitate a cessation from 

 microscopic work for some days. 



