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if necessary. That asepsis is better secured by this arrangement than 
by the chamber of Ninuwenavts, which is 8 m.m. high and quite 
open on one side, requires no further proof. 
My principal objection is, however, to the circumstance, that 
Nikuwennuis drags the isolated cell in the droplet over the glass to 
the culture drop. This he cannot avoid, as he uses a club shaped 
needle. 
In my dissertation I also transferred the cells by dragging, but, 
with a few exceptions, I have departed from this in later years. One 
of the reasons, which certainly may be advanced, is that this 
dragging, in the case of very small cells, fatigues the eye. The 
principal reason, however, is that the cells remain behind, especially 
in the case of long thin rodlike bacteria, spirillae, and spirochaetes. 
There are all sorts of cells which it is not possible to drag across, 
even in a large transport drop; such a drop has further the 
disadvantage that a contaminating bacterium is not readily dis- 
covered in it. NreuweNHuis states, that with him even spores some- 
times adhere to the lower surface of the coverslip. No wonder, 
especially if one further considers that the isolated droplet begins to 
evaporate in its journey across the chamber, which is open on one 
side. If a cell remains behind, he advises placing the knob behind 
it and then moving it on; he admits however that thus the danger 
of injury arises. It is evident that micro-organisms with long fine 
cilia are not improved by dragging along, and that one may safely 
call this a harmful physical stimulus. On account of all these reasons 
I use an eyelet in which I take up one cell, and place it at once 
without dragging it, next to the culture drop. Only in very few 
exceptional cases, as for instance when the cell for some reason or 
another could not be easily taken up in the eyelet, one can have 
recourse to this dragging (for which my eye-shaped needle can also 
be used), but with my method at least the transport-drop will not 
evaporate while on the way. I can as little welcome the modification 
of bringing “the cell at once into the culture-drop with the same 
needle with which it was isolated. 
NIEUWENHUIS says on p. 532: “it is clear that the parts to be trans- 
ferred must be as far as possible from one another in the drop of 
the material, in order to avoid a contamination of the needle; from 
this it follows that the material must be very dilute”. 
I willingly grant that when the cells occur far from one another 
in the drop, one can be fairly sure that on taking the cell out of 
the drop the needle will not be contaminated by the neighbouring 
cells. When, however, in a mixture only comparatively few cells 
