SCIENTIFIC SUMMARY. 
321 
Food for Ants.” The structures in question were discovered hy Mr. Belt 
(Nicaragua), and subsequently further observations made by Fritz Muller 
(Brazil), while Mr. Darwin has more particularly entered into their minute 
composition. In Acacia they are of two kinds, small, somewhat flattened, 
pear-shaped bodies, which tip six or seven of the lowermost leaflets of the 
bipinnate leaves. In Cecropia cylindrical bodies are developed in flat 
cushions at the base of the leaf stalk. Mr. Darwin shows the microscopic 
structure in all of these to be homologous in kind, cellular, protoplasmic, 
and containing oil-globules. He infers, moreover, they bear a relation to 
the serration-glands of Reinke, in certain cases afterwards being converted 
into stores of nutriment, which undoubtedly the ants live on, and in their 
turn protect the trees from the ravages of the leaf-cutting ants. — Linnean 
Society, June 1. 
Pythium Equiseti . — Great interest is just now attached to this curious 
parasite, and hitherto it has not been recorded as British. Dr. Sadebeck, 
of Berlin, described the plant last year as a new species of Pythium, para- 
sitic upon Equisetum arvense. Mr. W. Smith says (“ Gardener’s Chronicle ”) 
it bears a considerable resemblance to the bodies discovered last year, and 
referred by me to the secondary condition of the potato fungus. It ulti- 
mately appeared that Dr. Sadebeck also last year found a similar parasite 
infesting and destroying living potato plants near Coblenz, and at the time 
he referred the Equisetum and potato parasites to the same fungus, and on 
seeing my micro-photographs he doubtfully threw out the suggestion that 
all three fungi might possible prove to be the same with each other. On 
these insufficient grounds a report was spread in this country that the organ- 
isms described by me were the same with Dr. Sadebeck’s Pythium Equiseti, 
and the “ Journal of Botany ’’for March last stated, in reference to Pythium 
Equiseti, that it had “ lately been attempted to connect this fungus with the 
oospores of Peronospora infestans. 1 ’ Dr. Sadebeck can hardly be said to 
have made such an attempt, for in a very kind letter that he wrote me on 
March 23 last he said the presumed identity was a mere u supposition,” 
thrown out in a preliminary paper, that he was without experiments from 
which to form a definite conclusion, and that he had not been able to infect 
the potato plant artificially with the Pythium. Dr. Sadebeck’s excellent paper, 
and the evident strong external resemblance of his newly-discovered plant 
to mine, made me extremely desirous of seeing the Berlin plant, but on writ- 
ing to Dr. Sadebeck to this effect he replied that he had no specimens. It 
therefore only remained to look out for the parasite here, and I was fortunate 
enough to enlist the good services of Mr. B. D. Jackson, F.L.S., who sent me 
some capital specimens of Equisetum arvense from Snodland, Kent, on April 
25. The first piece of Equisetum I examined under the microscope displayed 
the presence of fungus spawn ramifying amongst the tissues ; so, from ex- 
perience gained of the habits of some of the lower fungi, I half submerged 
the specimens of Equisetum and kept them covered up in a dark place. In 
ten days the Equisetum plants were dotted inside and out with gelatinous 
patches, and every patch was a mass of Pythium Equisetum. Though 
bearing a strong resemblance to the early condition of the bodies found by 
me in the Chiswick potatos, yet Pythium Equiseti is clearly not the same. 
Mr. Berkeley, who has seen both plants, writes me that he considers them 
YOL. XV. — NO. LX. Y 
