EXPERIMENTS ON SPONTANEOUS GENERATION, ETC. 117 
by self-division (fission), but that the life-cycle in each case 
began and ended in a distinct genetic product — call them what 
we choose, spores, germs, or ova. 
In PI. CXXXIII. I have drawn from nature, in the six respec- 
tive cases, the condition presented by each organism at the time 
of emitting its spore. Fig. 1 is the genetic product of an oval 
monad, with a pair of flagella; it rapidly increased by 
fission ; then in a remarkable manner a pair blended, became 
one in the form of a sac, the sac burst and poured out, as the 
drawing portrays, innumerable spore, which were watched con- 
tinuously until they were seen to develope into the parent 
condition. Fig. 2 gives a similar product of another form, 
different anatomically and in all the details of metamorphosis, 
but yet passing through the states of fission, blending into a sac, 
and (as seen) the emission of spore ; which were again watched 
into the parent condition. Fig. 3 shows the direct genetic- 
product of a third, but this sac did not contain spore, but living 
young , which swam forth at once upon the bursting of the sac; 
and by taking in pabulum at all points of the sarcode, rapidly 
grew to the parent size. In fig. 4 we have new features. The 
organism is oval, with one flagellum. It multiplies with 
enormous rapidity by multiple fission,* and then by dis- 
tinct genetic union a sac is formed and spore emitted ; 
but they are packed in a glairy fluid, and were so 
minute that at first our best powers failed to reveal them. 
But they were afterwards seen, and their full development 
traced. In figs. 5 and 6 we have the same products of the two 
last monads. In morphological detail they greatly differed from 
all the preceding ones, and from each other. But the spore-sacs 
were produced by the same means, and the exquisitely minute 
spore poured forth were traced through all their stages to the 
adult condition. 
We have here, then, important indications of fact concerning 
the nearest allies of the bacteria : they develope from germs. 
We have besides, the weight of the best experimental evidence 
pointing clearly to the existence of germs in the bacteria them- 
selves. But the microscope has failed to demonstrate the latter. 
Its finest powers and finest methods failed to reach them. 
Happily at this juncture Professor Tyndall has stepped in, 
and, with his accustomed brilliance and precision, has opened 
up the path we need. He has presented us %vilh a physical 
demonstration of the existence of immeasurably minute 
molecules of matter — utterly beyond the reach of the most 
poiueiful combination of lenses yet constructed — which are 
the indispensable precursors of bacteria in sterilised in - 
* “ Monthly Micros. Journ.” vol. xi. pp. 69-70. 
