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Notes. 
PRELIMINARY NOTE ON SPONGOSPORA SOLANI, BRUNCH. — The 
organism named Spongospora Solani by Brunchorst (1), which has become generally 
distributed in Great Britain and Ireland, causes, as the direct result of its parasitic 
habit, the formation of scars and scabs of a more or less cankerous nature, in potato 
tubers, according to the conditions and virulence of the attack. These injuries have 
been called by various names, i. e. Corky Scab, Powdery Scab, Canker, &c. At the 
same time the potatoes may be stimulated to produce abnormal outgrowths. 
In spite of the interest aroused by Nawaschin’s (2) paper on Plasmodiophora , 
Spongospora has remained practically where Brunchorst left it nearly a quarter of 
a century ago. 
Brunchorst saw in this parasite an endophytic Myxomycete, possessing a plas- 
modium capable of entering and living within the cells of its host. This plasmodium 
at some period of its life-history becomes changed into a spongy, coherent mass of 
walled spores — a single mass or spore-ball in each cell. 
Spongospora , during what may be safely regarded as its earliest stage in the host 
tissue, appears in the form of uninucleate myxamoebae, so that the penetration of 
living host-cells, where this occurs, is accomplished, not by plasmodia, but by uninu- 
cleate bodies. The method of penetration, however, is still unknown. Massee (3), 
in 1904, announced the discovery of myxamoebae, but supposed them to belong to 
some other organism : in a subsequent paper (4), however, these bodies are described 
as the myxamoebae of Spongospora. The myxamoebae increase in number and their 
nuclei divide by the method observed by Nawaschin for the amoebae in Plasmodio- 
phora. Their extension into newly forming tissue is brought about owing to the 
fact that some of the myxamoebae enter each of the two daughter cells arising — by 
normal mitosis — from the originally infected tissue cell. 
Towards the close of the vegetative phase of the parasite the separate amoeboid 
bodies become approximated and grouped about the nucleus of the host-cell, so that 
a condition obtains analogous more to that occurring in the pseudo-plasmodia of the 
organisms enumerated by Olive (5) in the section Acrasieae of the group Sorophoreae, 
Zopf, than to that of the true (or fusion) plasmodia of the Myxogasteres. 
Nawaschin states that plasmodia are formed just prior to the generative phase in 
Plasmodiophora. It is impossible at present to state definitely whether this is the case 
or not in Spongospora. At all events the pseudoplasmodium (colony) — or perhaps 
the plasmodium — becomes converted into a single spongy spore-ball. This structure 
is not hollow as stated by Massee (6), and on this account cannot be formed in the way 
described by him. During the generative phase the nuclei divide karyokinetically, 
there are many striking nuclear appearances, some of which resemble the figures 
published by Harper (7) for Fuligo and by Jahn(8) for Ceratiomyxa. 
Encysted individuals or groups of individuals may be found which are similar to 
the microcysts of other Myxomycetes. 
Structures comparable to the chromidia figured by Prowazek (9) for Plasmodio- 
phora also occur during both phases of the life-history, but their character and mode of 
grouping vary during nuclear division. 
Royal College of Science, 
South Kensington. 
A. S. HORNE. 
