Jan. 29, 1917 
Mechanism of Tumor Growth in Crowngall 
i8r 
These results and recent ones with crowngall teratoids (bacterially 
induced embryomas) lead me to believe that not only the origin of 
fasciations but also of many other duplications is to be sought in local 
and feeble infections by a variety of deep-seated microorganisms. 
Duplicate vascular cylinders in the pith and scattered concentric 
cortical or medullary bundles do not occur normally in the internodes of 
Chrysanthemum, Nicotiana, Ricinus, or any of the higher plants I have 
worked with, so far as I have observed, but triple sheathing cylinders of 
xylem-phloem (the inner ones standing in pith) occur normally in some 
of the ferns (Matonia). Scattered concentric medullary bundles (with 
a central phloem) occur in the stems of various dicotyledons, but are 
regarded as anomalous, while concentric cortical bundles are said to be 
rare (Solereder). Some of the phenomena here described are therefore 
possibly to be regarded as,in the nature of reversions to earlier and more 
primitive stem structures or else as indications of premature develop¬ 
ment of tissues which are normally developed only toward the end of 
the life cycle of the plant. Since this paragraph was written I have 
found a paper by Martin Mobius (25) describing and figuring a 
concentric bundle with central phloem from the axis of inflorescence 
in Ricinus communis. This stimulated me to examine sections from 
numerous nodes and internodes of Ricinus, as well as from the tap 
root, hypocotyl, cotyledons, leaves, and axis of inflorescence with the 
following result: 
Concentric medullary bundles with phloem at the center are very 
numerous in the axis of inflorescence (Pi. 65, fig. 1); they occur 
sparingly in the nodes, and are present in branch-gaps immediately 
above the node (PI. 65, fig. 2). I did not find them elsewhere in the 
internodes. They were not seen in the taproot, hypocotyl, cotyle¬ 
dons, petioles, or leaf-gaps. 
Mobius gives reference to earlier literature on concentric bundles of 
this type, especially Russow (23) and Bergendal (24), and at the end 
of his paper a list of families in which they have been observed. 
I have not been able to find such bundles in any part of the Paris 
daisy, although they occur in the crowngall on this plant and normally 
in the pith of certain composite (Scorzonera hispanica and Trago - 
pogon pratensis). 
Finally, I repeated Dr. von Schrenk’s ammonia tests on cauliflower,, 
obtaining numerous magnificent proliferations which could only be 
attributed to the ammonia used, since no copper salts entered into the 
experiments. At first I painted on dilute ammonia, but later and much 
more satisfactorily (PL 48, 49) I exposed the plants for a few minutes 
in a tight box containing 10% cubic feet of air space to vapors from a 
small quantity (1 c. c., y 2 c. c., ^ c. c.) of aqua ammonia (0.90 sp. gr.). 
The vapor undoubtedly entered through the stomata which are chiefly 
67908 °— 17—■—2 
