344 GEORGE MASSEE [November 



pustules, therefore no comment is necessary ; only further experiments 

 in the same direction will be made in the future. 



Tradition acts as a powerful bias, even in scientific matters ; 

 immediately following De Bary's brilliant discovery of heteroecism, 

 the condition of rust on the Barberry alternating with that on some 

 graminaceous plant was considered indispensable for the continuation 

 of the species ; eventually it was discovered that the stage on Barberry 

 could be dispensed with, and yet the rust appeared as rampant as ever ; 

 in fact in Australia, where rust is more abundant and injurious than in 

 Europe, the aecidium condition is unknown ; in India also, where ruts 

 is very destructive, no aecidium condition is known to exist within 

 hundreds of miles of the wheat-growing districts. At the present day 

 it is generally accepted that the uredo-spores only retain their power 

 of germination for a very limited period, and that the uredo-spores 

 must be in contact with the host-plant to effect inoculation. The 

 experiment just recorded modifies this idea to some extent. Teleuto- 

 spores, again, are considered at present as being only able to infect the 

 host that bears the aecidium stage ; however, their production in such 

 immense numbers in those countries where no aecidium stage is pro- 

 duced, or required, suggests that they may possibly play some part in 

 the reproduction of the fungus hitherto undiscovered. 



Numerous preparations of rust-shrivelled grains of wheat have been 

 examined microscopically, and an abundance of mycelium detected in 

 the outer layers of the grain, correctly speaking, in the pericarp ; but 

 not in a single instance have I been able to detect mycelium in the 

 embryo ; and in those cases where the grains were allowed to germinate 

 and form a tiny plantlet up to half an inch in length, the mycelium 

 never appeared to pass into this part. On the other hand, when 

 sections of diseased wheat were placed in culture media, hyphae 

 frequently radiated from the section on all sides for some distance. 



May not similar hyphae radiate in the soil from diseased grain 

 when sown under natural conditions, vegetate for some time in a 

 saprophytic manner, and finally, if conditions are favourable, infect the 

 young plantlet at, or just below, the ground level ? Sufficient of 

 obviously rust-shrivelled grain is frequently used as seed ; and if, in 

 addition, plants are infested with mycelium, which for some at present 

 unknown reason does not produce spores, as I have shown to be the 

 case with Scilla bifolia, and also recorded by Bolley (11) as frequently 

 occurring in the case of wheat attacked by Tilletia levis, Ktihn ; and 

 assuming that this mycelium also passes into the grain, then we should 

 be able to account for a considerable quantity of the rust prevalent, 

 without introducing a new factor — mycoplasma — into the theory. 



Mycelium of the rust fungus has been observed in the grain of 

 wheat by Eriksson, as shown by the following quotation (12), and if 

 inoculation of the young plant is effected by means of mycelium 

 originating from the grain, and growing for a longer or shorter period 



