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1878 Radicles Phaseolus multiflorus. Geotropism tips greased & blackened.

(Grease)

The following was tried because out of 13 long radicles which had been thrice dubbed touched or rubbed on their tips. Dec. 1' 1878 with n. of silver & much blackened, 6 had tips bent at rt ∠ or hooked, showing that one side of apex had been killed, & these all grew out sub-horizontally, as if Geotropism destroyed — like Cieleski— Sachs disputes, but these neither know of effects of oblique slices, & we now know that irritating one side of apex determines bending. Therefore cutting off tip transversely probably destroys the coordinating power & radicle they grow lawlessly.— I fully believe from notes that 12/13 grew out sub-horizontally, certainly 6/13 did so

Dec. 4th 7 long radicle were fixed horizontally & on tip of each a dab, (Temp. about 66° kept in dark on Chimney Piece) dab about 2 mm (1 1/2 / 20 of inch) in length of thick olive oil & Lamp-black (used because at Hand) & 4 Control left, with no dabs.

The latter became bent, after 8° 30' & had tips turned more or less downwards, & only 1 with black tip. (After 24° from putting on dabs all white tips considerably bent down, 1 of black tips considerably 2 a little: most of the radicles were at first 45 m.m long, & 1 had increased during the above 24° 5 m.m, & another 7 m.m., & all had increased; & on following 24° they had increased in same manner & to about same degree, so that greased tips — no had not stopped growth. (After 48° from the first (ie. Dec. 6th) tips of most of blackened radicles turned perpendicularly down or obliques; so blackened tips

(over)

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do not destroy, but only check action of geotropism. (Dec. 8th (i.e. after 4 days — tips of all except one well turned down, & the terminal portion for a length of from 1 inch to 1.7 inch presented a very curious appearance for covered with longitudinal striae & dots of the blackened gum & the owing to the black dot which was at first only 2 mm in length having been drawn out to 1 or 1.7 inches i.e. 44 m or 22 times its original length!! It certainly seems clear that whatever disturbs growth of tip checks geotropism & we must remember that the chief growing & bending zone lies within or above the 2 mm. length of apex which was greased. —

Dec. 11th 8° am not one of black tips Radicle Killed though 1 much shorter— 4 white tips of almost exactly same length — 2 of Black tips equal or very nearly so in length to the white tips — the others shorter though (excepting one) not in any great degree— it is clear that black grease only slightly injurious.