400 Dr. H. Charlton Bastian on the Origin 
may see, under the highest power of our microscope, scarcely 
visible motionless specks gradually appear in increasing 
numbers in the midst of the structureless protoplasm ; and 
still later we may see some of these specks growing into 
Bacteria, as in Pl. XXVI. fig. 9, B, x 700, which is a repre- 
sentation of A after four days. At last the whole interior 
of the spine becomes filled with distinct Bacteria, as may be 
seen in C (x 700), which is from a photograph of the same 
spine on the sixth day—the temperature during these days 
varying from 70°-75° F. Later still, all the Bacteria, 
previously motionless, began to show active swarming move- 
ments. 
In such a case it is clear that we have to do with no pro- 
cess of infection from without, but with a de novo origin of 
Bacteria from the protoplasmic contents of the spines or sete. 
The fact that they appear in these situations as mere separate 
motionless specks, and gradually take on the forms of 
Bacteria (also motionless at first), is, as I have previously 
indicated, just what we might expect if they had actually 
taken origin in the places where they appear. On the other 
hand, such a mode of appearance is totally opposed to what 
might be expected if the microorganisms had obtained an 
entry from without, through the chitinous envelope of the 
spines. 
I pass now to what may be regarded as another absolute 
_ proof of the heterogenetic origin of Bacteria, as convincing 
as that which I have shown to occur within the closed cells 
of certain vegetables. 
I have already pointed out that in many parts of the bodies 
of man and of higher animals microorganisms are known to 
exist in abundance. This is the case, for instance, throughout 
the whole length of the alimentary tract, and throughout 
almost the whole extent of the mucous membranes of the 
respiratory tract. It is clear also that some of the micro- 
organisms may be taken up from these mucous membranes 
by lymphatics, and if they pass the nearest lymphatic glands 
some of them would ultimately find their way into the blood. 
When there, the view generally accepted is that the Bacteria 
and their allies are at once “destroyed.” The blood of 
healthy animals is declared to be germless, and much im- 
portance is attached to the germicidal qualities of this fluid. 
On the other hand, it has been found, as I have previously 
intimated (p. 884), that in organs contiguous to the alimen- 
tary canal—such as the kidney, the pancreas, the spleen, and 
the liver—taken from a healthy animal immediately after 
