18 ARKIV FÖR BOTANIK. BAND 12. NlO 1). 



unable to state with certainty whether amoebae wliich have 

 only a single nucleus are primary amoebae or have come into 

 existence as meronts by devision of schizonts. Statements 

 and figures in Maire and Tison^ of uninucleate and bi- 

 nucleate amoebae in Sorosphaera are presumably correct, 

 but such amoebae with apparently few nuclei are often 

 got by cutting off parts of a multinucleate amoeba. As, 

 however, the authors named state, that they have observed 

 a great quantity of uninucleate amoebae situated one or a 

 few together in each cell, we are led to the conclusion that 

 this is really the case, and that the amoebae are either able 

 to penetrate the cell-walls, so that the infection may have 

 spread in this way, or that the host-plant is infected while 

 still very young, and that the infection-amoeba at first un- 

 dergoes very frequent divisions, possibly divisions simultaneous 

 with the nuclear divisions, and that the parasite is distri- 

 buted solely by cell-divisions of the host-plant, and thus only 

 to daughter-cells originating from an originally infected cell. 

 It must be left to the future to decide which is the correct 

 assumption, but å priori it seems to me probable that the 

 young amoebae are able to penetrate cell-walls as well as 

 many, more animal-like, protozoa. What moreover leads us 

 to this conclusion, nay, what even seems a sufficient proof, 

 is, that often in tubers of Sorosphaera or Sorodiscus which 

 must be considered as originating from one infection, one 

 may find cells which are so distantly related, that the infec- 

 tion of a cell in the seedling would not be sufficient to ex- 

 plain the distribution. Both in Veronica and Callitriche it 

 is mainly the inner cortex and parts of the central cylinder 

 which contain spores, so that not even an infection of the 

 germ might result in so extensive an infestation if the fungus 

 did not spread actively. Ligniera Ju7ici likewise seems to 

 imply the wall-penetrating power of the myxamoebae, and 

 statements about the capability of the Ligniera graminis- 

 amoebae of sending pseudopodia right through the cell-walls 

 (Schwartz -6) as also the conditions in Pyrrhosorus marinus 

 JuEL^^ (see later on!) seem to confirm this assumption. 



The youngest stages of Sorodiscus which I have succeeded 

 in investigating are the amoeba-stage at a more advanced 

 stage, as I have only examined infections which have spread 

 a good deal, but never primarily infected cells. By such 



