22 



Besides the surface application of the germ, many slight abrasions 

 with a tine needle were made on the surfaces of the inoculated leaves 

 of three plants of each of the first three varieties of carnation men- 

 tioned. The house was kept shaded and the surface of the leaves was 

 moistened each day by a light sprinkling in order to give the germs a 

 good opportunity to develop, but not a single spot that could be attrib- 

 uted to the bacterial inoculation developed on any of the plants dur- 

 ing a period of six weeks. The abrasions in many instances showed 

 swollen edges and became slightly yellow, as in the case of the abra- 

 sions described by Arthur and Bolley. They did not increase in size 

 and could not be attributed to the action of the germ, especially as the 

 abrasions made on the control plants behaved in exactly the same 

 manner. 



ANTISEPTIC COLONIZATION. 



Four plants of each of the three varieties of carnations, or twelve 

 plants in all, were taken into the laboratory at the l)eginning of the 

 inoculation experiments and were placed under large bell jars. These 

 plants had a new growth which had never been injured by insects or 

 spiders and were perfectly free from spots. One plant of each variety 

 was used for a control experiment, no aphides ])eing permitted on them; 

 aphides were colonized on another lot, also consisting of one plant 

 of each variet}' ; and every leaf of another lot, consisting of two plants 

 of each varietv, was carefullv washed with corrosive sublimate solu- 

 tion, 1 to 1,000 parts of water, all the glaucescence being carefully 

 removed from the leaves and stems, it being easy in this wa}- to deter- 

 mine when the plants were thoroughly wet and consequently disin- 

 fected. Previous to this a colony of aphides {lihojKilosijyliuiii diantJd 

 Schrank) had been grown upon a similar!}' sterilized plant until there 

 were about 300. Out of this niunber 25 were selected at random, 

 mashed up, and cultures made from the mass, but these cidtures were 

 perfectly free from bacteria or fungi. Before colonizing the other 

 aphides thej" were allowed to crawl over the surface of moist agar in 

 test tubes to determine whether they were free from bacteria, and as 

 none of the latter developed, it was known that each individual used 

 in the colonization experiment was free from germs. 



The experiment was begun May IT, 5 aphides being put on each 

 plant except the controls. On May 20 several spots could be plainly 

 seen in the region where the aphides had been working on the most 

 rapidl}" growing joung leaves, and from this time on numerous spots 

 appeared. On ISIay 24, just one week after the aphides had been col- 

 onized, there were on one of the sterilized plants 30 aphides and 250 

 spots could be seen with the aid of a hand lens, on another there were 

 20 aphides and 170 spots, on a third 20 aphides and about 170 spots, 

 and on a fourth 40 aphides and about 250 spots. The other two plants 



