336 Osborn . — Spongospora snbterranea , ( Wallroth ) Johnson. 
paper described Sorcsphaera Veronicae in detail. The myxamoebae found 
in the leaves and stems of Veronica spp. contain, at first, a single nucleus 
with a karyosome, and chromatin on a linin network. - The division of this 
nucleus is ‘ une mitose d’idiochromatine combinee avec une amitose de tro- 
phochromatine ’. In this division an intranuclear spindle is described with 
centrosomes and polar radiations more or less visible. This stage is regarded 
as a ‘ schizont ’ condition of the organism, since small amoebae are constricted 
off from the larger ones. At the conclusion of this stage the nuclei are 
reconstituted, the chromatin passing out into the protoplasm, where it is 
found as chromidia. Later the contents of the nuclei reappear, synapsis 
follows, the nucleoli disappear, and chromosomes form. There is a double 
karyokinesis, the divisions of which are regarded as heterotypic and homo- 
typic, eight double chromosomes being visible in the former. During the 
second division the protoplasm becomes rounded about each nucleus, 
forming a spore, a number of which are arranged in a hollow sphere. 
Very similar results were obtained by Bloomfield and Schwartz, 1 only 
recorded in less detail. The point of infection was found to be at the 
growing apices, and the infection of fresh host cells was produced, not by 
the penetration of the cells by the amoebae, but by the subsequent divisions 
of the cell originally infected. In 5 . Veronicae there is much hypertrophy 
of the tissues, and the infected cells of the host become multinucleate. 
Schwartz 2 has more recently described a new species, Junci , the life- 
history of which is essentially the same, but no hypertrophy of the tissues of 
the host is produced. 
Before entering upon a discussion of the points of difference between 
Spongospora and the other members of the Plasmodiophoraceae, it will be 
useful to consider the recent work on the Mycetozoa. Following the early 
work of Strasburger and Lister 3 (who suggested an amitosis of the vegeta- 
tive nuclei in Badhamia utricularis ), Harper 4 gave a detailed account of 
the cell and nuclear divisions in Fuligo. In regard to the cell-divisions, his 
work was of importance in showing that they are independent of those of 
the nuclei, and result from a progressive cleavage of the plasmodium. 
In 1907 Fraulein Kranzlin 5 described the development of the sporangia 
in Arcyria and Trichia. Previous to spore formation the nuclei associate 
in pairs and a fusion occurs ; any nuclei that do not fuse quickly degenerate 
and disappear. The fusion is interpreted as karyogamy, and is followed by 
a temporary enlargement of the nucleus and a synapsis. The nuclei, on 
regaining their normal size, show an arrangement of eight double chromo- 
somes that is described as diakinesis. At the conclusion of this stage 
1 Bloomfield, J. E., and Schwartz, E. J. : loc. cit., 1910. 
2 Schwartz, E. J. : loc. cit., 1910. 
3 Lister, A. : loc. cit., 1893. 4 Harper, R. A. : loc. cit., 1900. 
5 Kranzlin, Helene : Archiv f. Protistenkunde, vol. ix, 1907, p. 170. 
