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POPULAR SCIENCE REVIEW. 
Bastian furnishes a correct illustration of a true pellicle. It is v 
always drawn too discreet and too uniform. The bacteria are 
always matted together in the closest manner, and millions of 
the minute germs of diverse lowly life-forms might be inter- 
spersed in that portion of the pellicle which constitutes the 
“ field ” of even the highest powers ; and I say advisedly that 
no microscopist in the world could ever distinguish them. 
It is now established that the monads produce germs or spore 
— and they are extremely minute. If such germs should be in- 
terspersed in a given pellicle, their earliest development could 
not he seen at all ; and when it had reached a certain stage it 
would only he visible under proper and definite conditions. 
But when the developing monad germ had reached say the size 
of a bacterium in the pellicle, I presume that Dr. Bastian would 
not claim any ability to distinguish the one from the other. 
Nevertheless fig. 14 is the copy of a drawing accepted by him 
from Pouchet as displaying the origin of u Monas lens” a is 
supposed to represent the pellicle, and the small aggregations in 
it are taken as the initial stage of the “ transformation ” of these 
organisms into monads ; this is said to go on, until a stage like 
that seen in b is reached ; and eventually a flagellated and com- 
plete form results, as seen at c. And this is presented as a case 
of heterogenesis. Now the fact is that the monad which is 
meant to be depicted here (hut which is badly drawn) arises in a 
germ — quite invisible unless looked for under special conditions, 
and not likely to be seen, with the appliances used, in a pellicle . 
But when this and other monad germs develope, as is constantly 
the case, in the pellicle, its growth and expansion, and probably 
other causes, modify, more or less plainly, the immediately sur- 
rounding portions of the pellicle, giving it an appearance similar 
to, but too strongly depicted at, a (fig. 14), the point indeed in 
which the bacteria are supposed to he transforming into monads. 
After this the germ rapidly progresses, the flagellum is acquired, 
and the perfect monad swims away. In fact it is no more a 
case of “ heterogenesis ” than is the birth of a humming-bird 
or an ox. And this explanation will apply in every instance ; 
the said 66 transformations ” are slightly altered conditions of the 
pellicle, resulting from the natural growth of interspersed monad 
germs. • 
But nowhere has the egregious mistake of this observer’s 
method so much impressed me as in the illustration on p. 220 
of vol. ii. of his “ Beginnings of Life.” I reproduce as much 
of it as is required in fig. 15; a a are monads which are sup- 
posed to have originated in the bacteria. At c c c these monads 
are ( 6t heterogenetically ”) changing, or changed into amoeba ?. 
At d d these amoebae are seen minus the flagella, in an active 
and a still condition. At e, /, g they have become encysted ; 
