51 



atoms at first derive sustenance from the rain-water washed 

 into the soil. After a short time these atoms, called zoospores 

 by some, myxamsebse by others, and swarm cells by De Bary, 

 unite together, and form plasmodia growths, either in the 

 soil, or in their host some cruciferous plant. The swarm cell 

 enters the young plant by the root hairs, according to some 

 writers. Zopf, in his Pilztkiere oder Schleimpilze, pays that 

 entry is made by the root hairs, or through the cuticle of the 

 young plant, and Sorauer agrees with this.* De Bary holds 

 that " the swarm cell with cilia penetrates without undergoing 

 division into the epidermis of the young root, and from thence 

 into the parenchymatous tissue."f Dr. Comes, the Professor 

 of Botany at the Royal Agricultural School at Pcrtici, accepts 

 De Bary's view of this entry, in his useful work, entitled 

 Crittogamia agraria. Mr. Worthington Smith, in his Diseases 

 of Field and Garden Crops, states that the plasmodia are 

 absorbed into the young plants by their rootlets. Further 

 experience has shown him that the plasmodia may also enter 

 through the first formed stomata of seedlings. Professor 

 Eycleshymer writes, that " the organism is supposed to penetrate 

 the root' hairs and thus gain access to the deeper parts of the 

 cortex. Repeated endeavours were made by means of slime 

 cultures to observe the penetration of these swarm cells, but 

 without success. This is a point that needs observation. The 

 penetration has never been .observed, and it is possible that it 

 is through ruptures in the tissue caused by insects and worms, 

 and other forms which are constantly present in the soil."J 



When the swarm cells have gained possession of a turnip 

 plant they form aggregations of plasmodia of a slightly yellow 

 colour, mobile, and increasing in volume as the cells of the root 

 tissue are broken down and their contents absorbed by the 

 invading slime fungus. All the food supplies of the plant are 

 concentrated upon these affected parts, which causes hypertrophy, 

 or unnatural enlargement, resulting in the swellings and de- 

 formities known as " Club-rcot." In these circumstances the 

 plants cannot grow properly and finally die, or become mere 

 distortions. 



The plasmodia in the roots of these infected plants may be 

 washed from them by rains, or they may move from them into 

 the ground with their peculiar streaming movement, and remain 

 centres of infection of future crops of brassicse. This power of 

 movement is remarkable, and is evidently used for the purpose 

 of seeking food supplies. Mr. Arthur Lister, in his most 

 interesting account of the plasmodium of Badhamia utricularis 

 and Brefeldia maxima, slime fungi, parasitic upon various 



* Handbuch der Pflanzenkrankheiten, Zweiter Theil, von Dr. Sorauer. 



t Comparative Morphology and Biology of the Fungi, Mycetozoa, and Bacteria, 

 by C. de Bary. 



J Club Root in the United States, by Professor Eycleshymer, in The Journal 

 of Mycology, published by the United States Department of Agriculture. 



D 2 



