22 ARKIV^ FÖR BOTANIK. BAND 12. N:0 9. 



the second and last nuclear division is entered upon. This 

 is a mitotic reduction-division which shows smaller nuclear 

 division figures than the former and only 4 double chromo- 

 somes of which 4 halves travel to each pole (fig. 47 — 52). 

 Thus binucleate amoebae again arise (fig. 51) in whose nuclei 

 the chromatin lies next to the nuclear membrane which has 

 now again become faintly visible. As regards Plasmodiophora 

 these amoebae have led Prowazek (1. c.) to the erroneous 

 conclusion that a nuclear fusion act takes place in this fungus. 

 The binucleate amoebae now divide into two (fig. 53), which 

 after having grown larger aggregate, most frequently more 

 tlian 30 at a time, and form a loose ball of uninucleate, still 

 walless spores (fig. 54). These spores are characteristic in 

 that their nucleus grows larger before the wall is formed 

 (fig. 55, 56) and by having, sometimes even after the forma- 

 tion of the wall, a distinct polar radiation from the side of 

 the nucleus directed towards the apex or to the basis of the 

 spore (fig. 58, 59). The nucleus now by degrees grows smaller 

 (fig. 57, 61, 60), at last it becomes quite tiny, and at the 

 formation of the wall the spores arranged themselves in 

 double cakes and assumed a characteristic form (see fig. 60, 

 62, 63) most frequently like a rounded six-cornered closed 

 urn which at the apex is provided with a ring-formed collar 

 — as it is also seen, though less plainly, in Sorosphaera Ve- 

 ronicae (fig. 70). At the full maturity of the spore-aggregation 

 the spore-wall divides into two layers of which the outer 

 one merges into that of the neighbouring spores, so that it 

 gives one the impression of the spores being deposited 

 in a common substance (fig. 60). This is what Schwartz ^-^ 

 means when after the setting up of his new Sorosphaera 

 Junci (now he proposes the genus-diagnosis altered into: 

 »Sporont, giving rise to wedgeshaped spores either loosely 

 aggregated or collected into spherical or ellipsoidal hollow 

 balls and usually enclosed by a common membrane.» 



It must be assumed, that the spore aggregations are set 

 free by the decomposition or the drying up of the host plant. 

 It is, however, not absolutely necessary for the aggregations 

 of spores to become decomposed at the germination, as each 

 single spore in a double cake is in touch with its surroundings. 

 On the whole in the various spore-arrangements of these endo- 

 phytical mycetozoa the principle always repeats itself that 



