188 THE POPULAR SCIENCE MONTHLY. 



always sufficed to kill Amoeba?, Monads, Euglence, Desmids, Rotifers, 

 Nematoids, and other minute aquatic organisms. The writer did not 

 try to ascertain what was the lowest temperature which w r ould prove 

 fatal to these organisms, though this has been done by other observers. 

 Spallanzani, for instance, ascertained that Ciliated Infusoria, Water- 

 fleas, Leeches, Nematoids, and other worm-like creatures, all perished 

 at 107-113 Fahr. ; while Max Schultze, 1 and Ktihne, 2 in part working 

 over the same ground, have quite recently fixed the limits for such or- 

 ganisms at temperatures varying between 104 and 113 Fahr. At 

 these temperatures the protoplasm entering into the formation of 

 such organisms as well as that of the tissue-elements of higher ani- 

 mals was not only killed, it became coagulated and assumed the con- 

 dition named by Ktihne "heat-rigidity." Both Max Schultze and 

 Ktihne also found that the protoplasm of plant-cells with which they 

 experimented was always similarly killed and altered by a very brief 

 exposure to a temperature of 118^- Fahr. as a maximum. All accu- 

 rate new observations, therefore, go to prove that different kinds of 

 living matter, whether in the form of germ or of developed organism, 

 are killed by a brief exposure in the moist state to a temperature at or 

 below 140 Fahr. 



2. So far I have been referring to the influence of heat upon liv- 

 ing matter when it is suddenly applied to an altogether unaccustomed 

 extent. This is the mode of operation with which we are especially 

 concerned, as, with the view to the interpretation of experiments on 

 the Origin-of-Life question, we wish to know the effects of great heat 

 upon organisms accustomed to ordinary atmospheric and aquatic tem- 

 peratures. On the other hand, it should be pointed out that organisms 

 have been found living in hot springs at temperatures very consider- 

 ably above those I have just been quoting ; although the very highest 

 of the temperatures, under the influence of which living things have 

 been reported as existing in thermal springs, is still a few degrees be- 

 low the boiling-point of water. The various observations that have 

 been made upon this subject have been collected and criticised with 

 much care by Prof. Jeffries Wyman, 3 to whose paper I would refer the 

 reader. The most remarkable instances of this kind, in which Con- 

 fervae, or allied organisms, have been met with that is, the highest 

 temperatures cited which are at all trustworthy are thus summarized 

 by Prof. Wyman : " The statements we have quoted," he says, " give 

 satisfactory proof that different kinds of plants may live in water of 

 various temperatures, as high as 168 Fahr., as observed by Dr. Hooker 

 in Sorujkund ; 174 as observed by Captain Strachey in Thibet ; 185 

 as observed by Humboldt in La Trinchera ; 199 as observed by Dr. 



1 " Das Protoplasma," Leipsic, 1863, pp. 33, 46. 



a " Untersuchung iiber das Protoplasma und die Contractilitat," Leipsic, 1864, pp. 

 46, 103. 



3 American Journal of Science and Arts, vol. xliv., September, 1867. 



