( 683 ) 
untere Hiilfte der Inflorescenz empor. Aber bei Weitem nicht alle 
Individuen werden hinreichend stark, um solches zu erreichen. 
“Handelt es sich somit darum, die Zwerge in möglichst schöner 
Entwickelung und voller Bliithenpracht zu cultiviren, so empfiellt 
es sich, sie stets durch spate Aussaat zu zweijährigen Exemplaren 
zn erziehen’’. *) 
It can be seen from the italicised portion of the above quotation 
that, considered objectively, the squat-shaped Oenothera nanella behaves 
as if in its development it has a resistance to overcome. If it succeeds 
in this, a normal apex is formed on the inflorescence. 
If the stem of a malformed nanella is cut through, one finds in 
part of the section the elements in groups filled with a black mass. 
This is most plainly shown ia the elements of the secondary wood ; 
these are often in a transverse section wholly black internally. This 
filling is found not only in the wood fibres, but also in the medullary 
ray cells; the wood-vessels are not as a rule wholly filled, but a 
similar substance lies here along the wail in the shape of a segment. 
The same applies to the cells of the pith, the cortex-parenchyma, the 
collenchyma and the epidermis. Nevertheless wholly filled cells can 
also be found in the cortex-parenchyma. 
This phenomenon appears in the same way in the root of Oeno- 
thera nanella. 
On looking at a section under a high power the black mass resolves 
itself into a large number of black spots which are evidently imbedded 
in a gelatinous matrix. With sufficiently strong magnification, especi- 
ally where the mass of cells which have been cut throngh, has 
spread more or less over the preparation, places are readily found, 
where the black dots lie so far apart that they can be made out 
separately. 
Every individual is surrounded by a lighter zone. The individuals 
are partly arranged in pairs or in fours, and are not of equally dark 
colour; the greater number are however opaque in the strongest 
illumination. 
The external characteristics leave no doubt that the organism 
seen in the tissue of Oenothera nanella is a bacterium of the genus 
Mierococcus. It does not differ from the Mierococcus in tooth -mucilage 
either in shape or size, though it is as a rule darker in colour. 
„ 
1) Die Mutationstheorie, Bd. I. p. 267 and 268. 
In the English edition is added Vol. I. p. 376: “These and other malformations 
of the dwarfs are often due to a disease and as such to a large degree dependent 
on outer circumstances; (note of 1908 ie 
This note is based on the investigation here published. 
