Thermal Death-iJoint of Monad Germs. By W.E.BaUinger. 9 



in vol. xi. of the ' Monthly Microscopical Journal,' pp. 69-72. A 

 piece of apparatus similar to Fig. 2 (and in diagram, Fig. 4) was 

 used. When the fluid containing the organism was properly in- 

 serted,* and time given for all to be at rest, a large number of the 

 organisms were seen by the lens in the cell C (Fig. 4). The whole 

 apparatus was now suspended in an oblong copper vessel with cold 

 water which covered the bulb A, and a thermometer was placed in 

 the water at each end of the vessel. This vessel of water was now 

 heated by means of a Bunsen burner, the gas jets of which ran 

 along -a tube the shape of the vessel, and crossed by another set of 

 jets in the middle of the parallelogram. The heat was applied 

 slowly, causing a very gradual increase of temperature. When 

 this had risen to 95" Fahr. the bulb was taken out and at once 

 placed in a prepared " cradle " on the stage of the Microscope. A 

 power of 400 diameters presented a field with seven of the forms. 

 It was in a state palpably distinguishable from that which would 

 be seen in a drop of the normal fluid. Four of the forms were 

 moving, but quite sluggishly. Two were wriggling their bodies 

 but efl'ectiDg no movement of translation, as seen in Fig. 6, Plate I., 

 where the dotted lines a, h and c, d show the positions taken 

 successively by the body of the monad ; but it neither advanced nor 

 receded ; while one form was quite still save for the lashing of the 

 flagellum laterally as indicated in the same figure by the dotted hnes 

 e, f, being the position into which the central flagellum waved itself 

 without intermission. But in seven minutes the former two had 

 entirely freed themselves and sailed away ; and the latter one, 

 e, f, had commenced a lateral movement of its body and in ten 

 minutes more was quite at liberty and swam freely. Eepeating 

 this process, the next point of heat tested was 110^ Fahr. When 

 the cell was examined there were nine monads in the field, seven 

 of which were slowly moving their flagella, and the other two were 

 merely jerking them at irregular intervals; but otherwise the 

 whole was still. There was nowhere any movement of translation 

 amongst them. But in the course of thirty-five minutes they had 

 every one passed through stages of increasing vigour, and all but 

 one had started off. The last moved sluggishly away in fifteen 

 minutes more. 



I next heated the fluid in a similar cell up to ISO'^ Fahr. Here, 

 on immediate examination, the effect was much more marked, for 

 over all the field there was total inaction, and this was the caso 

 in the entire cell. But fixing on a field with several still forms 

 in it, I noticed in two of the organisms a slight movement of the 



* This requirna a little skill in manipulation : the difficulty is tn cxcludo tiie 

 air and ins( rt tiic fluid. But tliis may 1)0 dono by using a picco of fine plutinum 

 wire, with a little of tiio lluid, as a piston ; drawing it V)aeKward8 and forwards, 

 the air comes out in bubbles, and the fluid takes its place. 



