BY J. ,1. FLETCHER AND C. T. >JUSSON. 23 1 



appeal to biologists in other countries, where Eucalypts are 

 acclimatised, to examine seedlings for the presence or absence of 

 axillary stem-nodules; and to record their observations. 



The problem, in which we hope our illustrations (certainly an 

 advance upon what has hitherto been attempted, though there 

 is scope for supplementing them), will arouse some interest, is 

 not a simple problem, that can be solved by anyone single-handed. 

 Even when the systematic botanist has done his share, the 

 problem, in its entirety, requires team-work — the active co-oper- 

 ation of the field-botanist, the phytopathologist who is an expert 

 bacteriologist, the morphologist, and the biochemist. The time 

 is ripe for its consideration. The Mallee Scrubs are steadily 

 vanishing in the more accessible districts of several of the States. 

 The investigations of Erwin Smith and some of his colleagues, 

 on Crown-Gall, reported in detail as to technique, the histology 

 of the tumours, &c., and well illustrated,"^ are available for the 

 bacteriologist as a starting-point. In addition, there are Erwin 

 Smith's " Bacterial Plant-Diseases'" (3 vols, already published), 

 besides his numerous papers on the subject of plant-tumours, as 

 well as Clayton Smith's paper; so that there is ample literature 

 to begin with. 



In Coville and Macdougall's " Desert Botanical Laboratory of 

 the Carnegie Institution," in Hornaday's "Camp-Fires on Desert 

 and Lava," and in Vols. xiii.,and xvi., of Contributions from the 

 U. S. National Museum, a number of characteristic, North 

 American desert plants are described, and in many cases illus- 

 trated. Some are said to have thickened, underground trunks, 

 or to be shrubs with numerous stems from a single root, or with 

 several stems clustered at the top of a thick, black root, or with 

 numerous stems given off from a thickened root. Some of them, 

 to us, are suggestive of the appearance and habit of the Austra- 

 lian Mallees. If the seedlings of the most remarkable of th^m 

 have not been investigated, we would call the attention of 

 American botanists to the advisability of examining these, in 

 order to test the current interpretations of the adult condition; 



* "Crown Gall of Plants: its Cause and Remedy," and "The Structure 

 and Development of Crown-Gall: a Plant-Cancer." Bulletin, Nos.213 

 (1911) and 25o(1912), Bureau of Plant Industry, U.S. Dept. of Agriculture. 



