34 BACTERIA IN RELATION TO PLANT DISEASES. 
Some of his experiments showed that the bacteria were carried over from seeds to 
seedlings. On the surface of the latter they were found in much greater numbers than on 
the seeds, particularly if the seedlings grew in closed dishes where the air was moist and 
dew often appeared on their surfaces. The occurrence of the same bacterial forms on the 
surface of mature leaves and stems suggests the way in which seeds and fruits become 
contaminated. 
The nutritional requirements of his yellow and red species appear to be very simple, 
since they. were able to obtain their carbon food and nitrogen food from many different 
substances. B. fluorescens and B. putidum were more exacting in their requirements. 
Fig. 4 shows masses of bacteria growing between the petals of the unopened flower 
of the hothouse carnation in what the writer has called the gum-bud disease of the car- 
nation. ‘They are seen to be entirely outside of the tissues. Subsequently the petals 
withered and the tissues were penetrated. At first the writer thought he had discovered a 
genuine bacterial disease, but further study indicated that the growing together of the 
petals on which depends the inability of the blossom to open normally, is the real cause of 
the disease and precedes the occurrence of the bacteria. The cause of this fusion of parts 
normally separate is unknown. 
In 1890, in the Annales of the 
Botanic Garden of Buitenzorg, in a 
paper on the flower buds of Spathodea 
campanulata, Dr. Treub mentions the 
fact that various bacteria occur nor- 
mally in the liquid secreted inside of 
the closed calyx. His statement is as 
follows: 
The relatively large quantity of or- 
ganic product [in the execreted fluid] ex- 
plains the very curious fact, that normally 
colonies of different micro-organisms de- 
velop in the liquid of the pitchers of the 
Spathodea without appearing to injure in 
any manner by their presence the floral 
organs in the process of development. 
The introduction of the microbes produc- 
ing these colonies may take place in two 
different ways: first, they may date from 
the. time when the very young calyx is 
still open; then, they may insinuate them- 
selves later into the narrow canal at the 
* summit of the pitcher and thus in the end 
Fig. 4.* arrive at the liquid. I am inclined to 
believe the second mode of introduction 
is the more frequent. In view of this fact it is not astonishing that the liquid contents of the perianth 
of the Spathodea campanulata is more or less putrid and ammoniacal. 
In 1897, in a long paper on the Hydatodes of the blossom buds of some tropical plants, 
Mr. S. H. Korrders, in the same Annales, also refers to the “‘constant occurrence of bacteria 
or fungus threads in the interior of water calyces.’’ He mentions bacteria as occurring in 
the flower buds of Spathodea campanulata, Clerodendron minahassae, and Kigelia pinnata. 
In the flower budsof other plants he found fungi. Sofar as he wasable to observe, only one 
fungus species occurred in one sort of water-calyx plant, although one would naturally 
expect mixtures. In case of bacterial growths the reaction of the fluid inside the calyx 
*Fic. 4.—Gum-bud disease of carnations. Cross-section of a Scott carnation, showing bacteria lying between 
outer petals of unopened bud. The petals are stuck together (grown together in many cases) and unable to open. 
Bacteria not in the tissues, and cause of disease unknown. Syringe-water contaminated by manure-water. March 
1903. Glen Burnie, Md. 
a 
