204 
NOTES AND MEMORANDA. 
organisms, making manifest tke periods of greatest fissional intensity ; 
and also showing the result following on the cessation of fission. In 
the majority of cases it was an exhaustion of vital action and death ; 
but in a certain proportion, in which fission was not so long continued, 
it was a rapid change to an amoeboid condition, resulting in the 
absorption or fusing of the lateral flagella with the body, and a change 
of form ; the organism becoming now quite oval and having only an 
anterior flagellum. It swims easily, but has lost all the power and 
freedom of motion possessed before, moving only in a straight line. 
But it soon comes into contact with a colony of the organism in 
the springing condition, attaches itself to one of them, which then 
soon unanchors, and both swim away. In the course of time their 
movements become sluggish ; the sarcode of the bodies is palpably 
blending, they become quite still, except for amoeboid movements, and 
then become one mass, oval in form, which elongates into a spindle- 
shape, remaining motionless and still in all respects for three or four 
hours ; when, as was ultimately and by long-continued effort made 
out, it pours out exquisitely minute, opaque, apparently round specks, 
which, when carefully and steadily followed with the best appliances, 
were seen to develop into the adult form and size. 
The author then desired to discover the relative heat-resisting 
power of the perfect form, and the germ or spore. The adult forms 
were proved by a very direct method, which was fully detailed, to be 
wholly destroyed at a temperature of 142° Fahr. Two methods of 
heating were employed to test the resistance of the spore. One was 
the “ dry ” method which had been employed in the former researches ; 
but which was somewhat modified and used with special precautions ; 
and the result of an elaborate series of experiments proved, that by 
this mode of heating, the spore could resist a temperature of 250° 
Fahr. 
It was next determined to test the heat resistance of the spores 
when they suffered the heat, diffused in a fluid. The difficulty of ac- 
complishing this, so as to secure an unmistakable result, was carefully 
pointed out and dwelt on ; and the opinion recently expressed by 
Dr. Bastian that it was “ perfectly easy ” shown to be an error. 
The apparatus employed for the purpose was specially delicate, 
but enabled the author to test directly the results of heat on the 
spores as well as on the adult organism, without exposure after the 
vessel was once sealed. The form used was specially devised for 
these observations. The temperatures up to the boiling point of water 
were got in melted paraffin, and higher temperatures in a digester. 
The result was that 220° Fahr. was found to be the limit of tempera- 
ture which the spore of this organism could endure without destruction 
of vitality. That is to say, 30° Fahr. lower than the same spores 
could bear in a “ dry ” heat. But it was pointed out, that to endure 
this temperature, implied protection of some kind ; but that this in 
the undeveloping germ was not only capable of being understood, but 
would doubtless prove of immense value to the organism.* 
* ‘ Nature,’ No. 447, p. 102. 
