( 654 ) 
It would appear that the Mtcrococeus forms a zoogloea, which fills 
the whole fibre or cell. There is, as a rule, in the preparations, a 
space between the cell-wall and its contents, though the latter has 
often so exactly the same polygonal outline as the cell, that there 
can be little doubt that the contents only retracted from the wall in 
the making of the preparation. 
Other organisms than the Micrococcus have not up to the present 
been found. 
Although therefore on the one hand Oenothera nanella with its 
contracted shoots has the appearance of a diseased plant, and on the 
other hand there is found in its tissues an organism, that may very 
well be the cause of the disease proof remains to be given, that 
Microceccus is indeed the agent producing the malformation. At the 
same time the question waits for a further answer, how it can be 
explained that on the origin by mutation of Oenothera nanella the 
diseased form always occurred and that the first normal plant was 
only obtained many years later. 
The appended figure of an Oenothera nanella with two kinds of 
shoots was prepared from a photograph made on the 27 of Sept. 
1905 in the Botanic Garden at Amsterdam from a fully grown plant. 
The shoot on the extreme right was 33 ¢.m. high. In the middle 
a diseased shoot is seen, with closely packed leaves. The top of this 
shoot is added from another specimen drawn from nature, in order 
to show the difference between normal and abnormal flower buds. 
In the diseased shoot, the calyx-tube is curved, so that the calyx 
and the corolla make almost a right angle with the axis of the 
ovary, whilst in the normal shoot the different parts of the floral 
bud lie in one straight line. 
The diseased shoots, have much shorter and thicker internodes 
than the healthy shoots. 
The leaves of the true Ovnothera nanella completely resemble 
those of O. Lamarckiana, except for the size. Those of the aberrant 
shoots are on the contrary provided with very short brittle petioles 
and broad short laminae. , 
Healthy shoots have up to the present only been observed excep- 
tionally. The reason is partly to be found in the fact that the normal 
nanella wholly resembles a dwarf Lamarckiana, and in the method 
employed, of examination as young seedlings, can be mistaken for 
the latter. 
On the other hand we must take into account, that attempts to 
obtain seed from healthy shoots have been unsuccessful. These shoots 
generally appear later on the plant and bloom too late for their 
