346 Journal of Agricultural Research voi. xix, no. s 



Not only the conditions governing the inoculations but even the 

 methods used were widely different in the two experiments. Lee (4) 

 describes his method of inoculating as follows: 



In making the inoculations an infusion of the organism was painted upon the 

 leaf blade, midrib, petiole, or stem, as the case might be, with a small camel 's-hair 

 brush, and then the tissue was punct\u-ed through the coating of infusion with a 

 needle. The inoculated twig was maintained in a moist condition by wrapping it 

 in paraffin paper, including with the twig also a small piece of moistened cotton. 



The senior author of the present paper, on the other hand, used infu- 

 sions of the canker organism, which were sprayed directly on the plants 

 in the screened cases by means of an atomizer. In no case were punctures 

 resorted to, although wounds and scratches were present at all times on 

 some of the leaves. It should also be noted that natural infections took 

 place from the more susceptible plants to the majority of the wild relatives. 

 (See dates of inoculations, p. 340.) Natural infections could be counted 

 on in the greenhouse cases, because the plants were set close together and 

 intermixed, and in addition a thorough syringing with a strong water 

 pressure was applied whenever the plants were watered. No infections 

 occurred on any of the rather remote wild relatives of Citrus until several 

 weeks after the last inoculation. This may be due either to the resistance 

 of the plants and the subsequent period of accommodation of the organ- 

 ism to the host or to the rather extended period of incubation. The 

 last statement appears to be more nearly correct and is substantiated by 

 Lee's results. 



Of the rutaceous plants not closely related to the genus Citrus positive 

 infections have been obtained on Casimiroa edidis, Chalcas exotica, and 

 Claticena lansium. Lee has successfully inoculated the last two plants 

 and, in addition, Evodia ridleyei, E. latifolia, Melicope triphylla, and 

 Toddalia asiatica. Both of us have failed to produce any infection on 

 Xanthoxylum spp., while so far Glycosmis pentaphylla has remained 

 immune. 



Jehle (j, 2) reports successful needle-prick inoculations on Xantho- 

 xylum fagara (L.) Sarg. and X. dava-hercules (L.) Sarg. He also obtained 

 watery swelling on Chalcas (Murraea) exotica. In all cases, a few non- 

 typical, unruptured spots have been produced at wounds or scratches 

 only. (PI. 59.) Of the plants infected, Chalcas exotica responds the 

 least, and the period of incubation is long. Lee likewise obtained only 

 a very weak reaction. 



No doubt other plants widely removed from the genus Citrus will be 

 successfully inoculated under certain conditions, although it is extremely 

 doubtful if any of the plants in this group will prove susceptible enough 

 to warrant any attention except to be of interest from a scientific stand- 

 point. 



In the subtribe Aeglinae, of the tribe Citreae, Chaetospermum gluti- 

 nosum is susceptible enough to rank with some of the Citrus fruits in 



