254 ROMANCE OF LOW LIFE AMONGST PLANTS. 



For example, it is contended that when the pro- 

 myceHal spores of Puccinia are sown upon berberry 

 leaves, the berberry yEcidium is produced by artificial 

 cultivation. In nature we have seen a berberry bush 

 in full vigour growing in the hedge of a large wheat- 

 field without the ^cidium upon a single leaf. Which 

 fact carries the greatest weight ? 



If the believers in hetercecism do not believe that 

 the berberry ^cidiuni is an integral part in the life- 

 history of the wheat-mildew, why do they persistently 

 urge the destruction of all berberry bushes in the 

 interest of the farmer ? If they do believe in it, why 

 have not the enormous preponderance of Puccinia 

 spores long since killed off every berberry bush in 

 Britain by infecting every living leaf ? 



The method of proof furnished in support of this 

 hypothesis may be gathered from the report of De 

 Bary's experiments in 1865. " He selected the rest- 

 ing spores (teleutospores) of the Puccinia, and 

 having caused them to germinate in a moist atmo- 

 sphere, he placed fragments of the leaves on which 

 they had developed their secondary spores on young 

 but full-grown berberry leaves, under the same atmo- 

 spheric conditions. In from twenty-four to forty- 

 eight hours a quantity of the germinating threads 

 had bored through the walls and penetrated amongst 

 the subjacent cells. This took place both on the 

 upper and under surface of the leaves. Since, in 

 former experiments, it appeared that the spores would 

 penetrate only in those cases where the plant was 

 adapted to develop the parasite, the connection be- 

 tween Puccinia graminis and ^cidiiim berberidis 



