NOTKN ON KECENT RESEARCH. 



an Intercellular mycelium produced by spore -infection and Living for 

 some time in the host-plant before it gives rise; to HporeH. Kriksson 

 .shows that no one has traced such a mycelium except near the ipore 

 sori, and just prior to their formation ; his own observations confirm 

 this. Another opinion is that the rust may arise from spores adherent to 



the husk of the grain or enclosed inside it. Eriksson says that adherent 



spores have been rarely recorded, while examination on his part shows 

 only occasional cases, fcco few to account for the general appearance of 

 rust throughout a whole field. Bporei have never been observed in or near 

 the embryo of the grain; they are always on or just below the husk. 

 Experiments with grains with adherent spores show that these are not 

 more liable to rust than clean grains, or those treated with fungicides. 

 Current theories thus disposed of, Kriksson describes his "myco 

 plasmic intracellular condition as a source of the disease." The gem 

 could not be discovered by any known methods of microtechnique till 



just before the appearance of the uredO'Sori. At this time, by using 8'fi 



per cent, alcoholic luematoxylin, then 2 per cent, alum solution, and 

 examining in glycerine, one can detect certain corpuscles floating in the 



cytoplasm, either isolated or in groups, Irregular in outline and sometimes 

 branched (plate 8). These are said to perforate the cell-wall and emit an 

 intercellular mycelium, the corpuscles themselves remaining in the, cell as 

 Buckers. (It seems yet not quite clear whether the corpuscles produce the 

 mycelium, or whether they are the suckers produce! by the mycelium.) 

 Eriksson's view is that the corpuscles are the visible product of a peculiar 

 form of mycoplasm unrevoalablc by existing methods, and Living in an 

 intimate symbiosis with the cell contents of the host -plant. The presence 

 of the mycoplasm does not appear to affect the host plant much. In the 

 grain it lives almost as long as tin: embryo plant itself, so that seed- 

 grain several years old is as likely to produce mated plants as thai 

 grown last year. Grain deformed and shrivelled by rust may give a 

 good crop, and vice versa, Plate 4 shows a variety of Wheat rusted 



in 1890 and 1 892, healthy in 1 ho J and 1898. Bust epidemics appeal 

 to depend on the weather in April, but the exact conditions have riot been 

 elucidated. 



Part III. (pp. 180 L52). Recent work in other countries. Since the 

 mycoplasm theory introduces into plant pathology a new mode of propaga- 

 tion of fungi, it has naturally led other workers to make observations; 

 generally, it must be said, with results antagonistic to Kriksson. This 

 chapter gives a critical review of recent work, and an attempt is made to 

 read the results into a confirmation of the mycoplasm theory. 



Part IV. (pp. 108 10.0). What is to be done in the suppression of 

 grain-rust V If Eriksson's views be accepted, then the destruction of 

 Barberry, treatment of seed by fungicides, and other such measures are 

 useless. Kriksson suggests a special experimental station in each country 

 where rusts of cereals are epidemic. The work of the stations is to find 

 out (a) which varieties are liable to rust, and therefore should not be culti- 

 vated ; (b) which are rust-proof ; (c) to determine how far soil, situation, 

 manure, season, Ac. are responsible for epidemics ; id) to obtain new 

 varieties of rust-proof cereals. The investigators should hold periodic 

 international conferences. — W. G. S. 



