As he passed my window I saw great clots of mud on his dusty
sabots, from the heels of which projected wisps of red wheat straw. Then I walked back into the Red Admiral's study, determined to find
what the microscope would show on the wheat straws. I examined each
one very carefully, and then, my eyes aching, I rested my chin on my
hand and leaned back in the chair. I had not been as fortunate as some
detectives, for there was no evidence that the straws had ever been
used in a sabot at all. Furthermore, directly across the hallway stood
a carved Breton chest, and now I noticed for the first time that, from
beneath the closed lid, dozens of similar red wheat straws projected,
bent exactly as mine were bent by the weight of the lid. I yawned in disgust. It was apparent that I was not cut out for a
detective, and I bitterly pondered over the difference between clews in
real life and clews in a detective story. After a while I rose, walked
over to the chest and opened the lid. The interior was wadded with
the red wheat straws, and on this wadding lay two curious glass jars,
two or three small vials, several empty bottles labelled chloroform, a
collecting jar of cyanide of potassium, and a book. In a farther corner
of the chest were some letters bearing English stamps, and also the
torn coverings of two parcels, all from England, and all directed to
the Red Admiral under his proper name of "Sieur Louis Jean Terrec, St.
Gildas, par Moëlan, Finistère." All these traps I carried over to the desk, shut the lid of the chest,
and sat down to read the letters. They were written in commercial
French, evidently by an Englishman. Freely translated, the contents of the first letter were as follows:

                                        "LONDON, _June 12, 1894_. "DEAR MONSIEUR (_sic_): Your kind favour of the 19th inst. received and contents noted. The latest work on the
     Lepidoptera of England is Blowzer's How to catch British
     Butterflies, with notes and tables, and an introduction by
     Sir Thomas Sniffer. The price of this work (in one volume,
     calf) is £5 or 125 francs of French money. A post-office
     order will receive our prompt attention. We beg to remain,

                               "Yours, etc.,
                                      "FRADLEY & TOOMER,
                               "470 Regent Square, London, S. W."

The next letter was even less interesting. It merely stated that the
money had been received and the book would be forwarded. The third
engaged my attention, and I shall quote it, the translation being a
free one:

     "DEAR SIR: Your letter of the 1st of July was duly received,
     and we at once referred it to Mr. Fradley himself. Mr. Fradley
     being much interested in your question, sent your letter to
     Professor Schweineri, of the Berlin Entomological Society,
     whose note Blowzer refers to on page 630, in his How to catch
     British Butterflies. We have just received an answer from
     Professor Schweineri, which we translate into French--(see
     inclosed slip). Professor Schweineri begs to present to you
     two jars of cythyl, prepared under his own supervision. We
     forward the same to you. Trusting that you will find
     everything satisfactory, we remain,

                                        "Yours sincerely,
                                              "FRADLEY & TOOMER." The inclosed slip read as follows:

     "Messrs. FRADLEY & TOOMER,

     "GENTLEMEN: Cythaline, a complex hydrocarbon, was first used
     by Professor Schnoot, of Antwerp, a year ago. I discovered
     an analogous formula about the same time and named it cythyl. I have used it with great success everywhere. It is as
     certain as a magnet. I beg to present you three small jars,
     and would be pleased to have you forward two of them to your
     correspondent in St. Gildas with my compliments. Blowzer's
     quotation of me, on page 630 of his glorious work, How to
     catch British Butterflies, is correct. "Yours, etc.,
                                      "HEINRICH SCHWEINERI,
                                        P.H.D., D.D., D.S., M.S." When I had finished this letter I folded it up and put it into my
pocket with the others. Then I opened Blowzer's valuable work, How to
catch British Butterflies, and turned to page 630. Now, although the Red Admiral could only have acquired the book very
recently, and although all the other pages were perfectly clean, this
particular page was thumbed black, and heavy pencil marks inclosed a
paragraph at the bottom of the page. This is the paragraph:

     "Professor Schweineri says: 'Of the two old methods used by
     collectors for the capture of the swift-winged, high-flying
     Apatura Iris, or Purple Emperor, the first, which was using a
     long-handled net, proved successful once in a thousand times;
     and the second, the placing of bait upon the ground, such as
     decayed meat, dead cats, rats, etc., was not only disagreeable,
     even for an enthusiastic collector, but also very uncertain. Once in five hundred times would the splendid butterfly leave
     the tops of his favourite oak trees to circle about the fetid
     bait offered. I have found cythyl a perfectly sure bait to
     draw this beautiful butterfly to the ground, where it can be
     easily captured. An ounce of cythyl placed in a yellow saucer
     under an oak tree, will draw to it every Apatura Iris within
     a radius of twenty miles. So, if any collector who possesses
     a little cythyl, even though it be in a sealed bottle in his
     pocket--if such a collector does not find a single Apatura
     Iris fluttering close about him within an hour, let him be
     satisfied that the Apatura Iris does not inhabit his country.'" When I had finished reading this note I sat for a long while thinking
hard. Then I examined the two jars. They were labelled "_Cythyl_." One
was full, the other _nearly full_. "The rest must be on the corpse
of the Red Admiral," I thought, "no matter if it is in a corked
bottle----"

I took all the things back to the chest, laid them carefully on the
straw, and closed the lid. The gendarme sentinel at the gate saluted me
respectfully as I crossed over to the Groix Inn. The Inn was surrounded
by an excited crowd, and the hallway was choked with gendarmes and
peasants. On every side they greeted me cordially, announcing that the
real murderer was caught; but I pushed by them without a word and ran
upstairs to find Lys. She opened her door when I knocked and threw both
arms about my neck. I took her to my breast and kissed her. After a
moment I asked her if she would obey me no matter what I commanded, and
she said she would, with a proud humility that touched me. "Then go at once to Yvette in St. Julien," I said. "Ask her to harness
the dog-cart and drive you to the convent in Quimperlé. Wait for me
there. Will you do this without questioning me, my darling?"