a chemical weapon ever,” Ms. Pierce said.

She also brought some of her own literary references. Responding to Mr. Nebenzya, who a few weeks ago compared British investigators on the case to the hapless Inspector Lestrade from the Sherlock Holmes stories, Ms. Pierce compared Russia to Holmes’s nemesis, Professor Moriarty.

A new challenge could come within a few days if Viktoria Skripal, Mr. Skripal’s niece, follows through on plans to travel to Britain. Alexander Yakovenko, the Russian ambassador in London, said at a news conference on Thursday that he had offered Ms. Skripal assistance with transport, accommodation and Russian-English translation during her visit.

Viktoria Skripal has repeatedly expressed doubts about the British accusations, suggesting that her relatives could have been sickened by bad fish or attacked by the mother of Yulia(P), potassium (K) contents of both ryegrass species were greatest in the emerging leaves and least in the mature leaves. The As treatment reduced biomass more in the mature leaves and expanded leaves relative to the emerging leaves for annual ryegrass and reduced more in emerging leaves relative to the mature and expanded leaves for perennial ryegrass. Perennial ryegrass had higher As content than annual ryegrass in all three kinds of leaves. The As treatment increased hydrogen peroxide (H2O2) in expanded leaves of two ryegrass species, relative to the control. The As treatment increased the ascorbate peroxidase (APX) activity in the expanded leaves of perennial ryegrass and the mature leaves of annual ryegrass, the catalase (CAT) activity in the mature and expanded leaves of perennial ryegrass and the