EXPERIMENTS ON SPONTANEOUS GENERATION, ETC. 125 
retained at a temperature, if the time of heating and cooling he 
considered, over 230° F. for one hour. This flask was opened after 
nine weeks. The reaction was acid ; the odour was not striking. 
On microscopical examination with a inch objective “ there 
appeared more than a dozen very active monads .” 
Now, fortunately, Dr. Bastian has not only carefully measured 
and described these organisms, but he has drawn them, and 
they are reproduced on the frontispiece of the book. He 
describes them as the l-4000th of an inch in diameter ; they 
were provided with a long, rapidly moving lash (flagellum), by 
which granules were freely moved about. But, besides this, 
“there were many smaller , motionless , tailless spherules , 
of different sizes , whose body-substances presented a similar 
appearance to that of the monads — and of which they were in 
all probability earlier developmental forms.” * 
Now, by careful comparison, I find that this monad is no 
other than the 44 uniflagellate monad,” which is the fourth in the 
series whose life-histories were studied by Dr. Drysdale and my- 
self.f Figs. 7 and 8, PL CXXXIII., will help to make this clear, 
where fig. 7 is an exact rendering of Dr. Bastian’s monad magni- 
fied 800 diameters ; and fig. 8 is a drawing of the “ uniflagel- 
late monad ” described by my colleague and myself, magnified 
2,500 diameters. We describe it thus : — 44 Its exterior form is 
extremely simple, being ovoid, with a single flagellum. Its long 
diameter never exceeds the l-4000th part of an inch ” in length.J 
Now, from a very prolonged and careful study of these organ- 
isms, I am convinced that Dr. Bastian’s form and ours are ab- 
solutely identical. But to make the thing simply irresistible 
we have further and final evidence. One of the metamorphoses 
■of this monad on its passage to multiple fission is that it loses 
its flagellum, and becomes precisely what Dr. Bastian saw all 
.•around — a motionless spherule.” § These little bodies are less 
in diameter than the active monad, and of precisely the same 
structure. The identity is thus complete. The evidence is as 
full as may be ; the monad Dr. Bastian saw was the one whose 
life-history was fully worked out. As usual, it multiplies by 
fission, but the fission is multiple. It then passes to a sac-like 
•condition, resulting from the uniting together or -fusion of two 
individuals. This sac becomes still and bursts, as seen in fig. 
4, pouring out spore that taxed our highest powers and closest 
watching. The spore of only two of the monads studied sur- 
vived after exposure to a temperature of 300° F. This is one 
of them . 
Now, Dr. Bastian says, 44 A drop of the fluid containing several 
* u Evolution,” p. 178. t “ Monthly Micros. Journ.” vol. xi. p. 69, et seq . 
x p. 69, ibid. § P. 69, ibid. 
