Relationship to the Mycetozoa and the Chytrideae . 235 
Quite recently Jahn (7) has observed a conjugation of the myxamoebae 
formed after the germination of the spores, and has stated that his original 
contention of a karogamy prior to spore formation was due to an error. 
The nuclear fusions he had previously seen he now considers as a con- 
comitant of nuclear degeneration, and not as sexual fusions. The reasons 
he assigns for this view are ample — viz. that the fusions are occasional, and 
do not give the appearance of a universal or simultaneous karyogamy ; the 
fusions are also to be found in the stalk and in the neighbourhood of the 
membrane, and are accompanied by degeneration. Similar nuclear fusions 
have been observed by Winkler in the disorganizing tapetal cells of 
developing anthers. In Jahn’s paper (7) on the sexuality of the Mycetozoa, 
published in 1911, he states that the swarm-cells are haploid, whereas the 
nuclei of the plasmodia are diploid, so that the sexual fusion is to be 
looked for at the commencement of plasmodium formation, and not at the 
stage preceding spore development. He figures mitoses in the haploid 
amoebae of Physarum didermoides , and diploid mitoses in young plasmodia, 
and he also figures a nuclear fusion of two haploid myxamoebae ; he finds 
also typical karyokinetic divisions of the plasmodium nuclei. 
The spores of the Mycetozoa, when germinated, as a rule give rise to 
ciliate swarm-cells, one of which emerges from each spore. In the exo- 
sporous Ceratiomyxa , however, each spore gives rise to eight swarm-cells, 
and in a few species of the endosporous Mycetozoa we get two or four 
swarm-cells from each spore. This I have observed to be the case in 
Comatricha obtusata , the spores of which each give rise to two swarm-cells. 
I have germinated the spores of Fidigo septica and Lycogala minicitum ; the 
swarm-cells of the former are shown in Fig. n. The Ftdigo spores 
germinate in half an hour in rain-water if they are previously broken up by 
crushing them on a microscope slide, otherwise the germination is extremely 
uncertain, only one culture out of ten showing germination after three days ; 
the spores, if kept for a week or more, lose their power of rapid germination. 
The swarm-cell is pear-shaped, and has a long flagellum at the pointed end, 
at which end also the nucleus is situated. The swarming lasts for about 
thirty hours and is followed by temporary encystment ; after two or three 
days a few amoebae or small plasmodia may occasionally be seen. I have 
not succeeded in cultivating the organism beyond this stage. 
Strasburger’s statement that a simultaneous division of the nuclei of 
the developing sporangium takes place just prior to spore formation I have 
verified in the case of Lycogala miniatum> and this karyokinetic division is 
shown in Figs. 12 and 13. 
The development of the sporangium of Arcyria ferruginea shows con- 
siderable difference to that of a typical endosporous Mycetozoon. In place 
of the universal karyokinetic division of the nuclei and consequent simul- 
taneous formation and ripening of the spores we get a gradual or successive 
