WINGE, CYTOLOG. STUDIES IN THE PLASMODIOPHORACE^. 33 



in roots or such which attack the above-ground parts. At 

 the copulation the nuclei become 2 x chromosomes and keep 

 this number during the vegetative phase and until the second 

 sporogonic division when the reduction takes place. The in- 

 fection-plasms penetrate the cell-walls (comp, also Pyrrliosorus) 

 and travel, at any rate as regards a number of Plasmodio- 

 phoraceae, actively towards the central tissues and are likewise 

 distributed by the cell-divisions of the host-plant, so much 

 the more as the infection frequently takes place in zones 

 with lively growth and the organs are forced into especially 

 frequent divisions. — After the formation of the spores follows 

 a resting period until the host-plant is dead and the spores 

 are set free by its decomposition. The germination of these 

 spores takes place again the following spring. 



It is, however, not impossible that it will be found that 

 in the Plasmodiophoraceae further karyokinetic divisions may 

 take place at the germination of the spore. 



Arkiv för botanik. Band 12. N:o 9. 



