My dear Father,

Stahl knows about the growth on A. pectinata; & I think the thing you saw must certainly be it: he says if you sent 2 or 3 leaves or a tiny twig in a letter he could tell at once as the fungus grows all through the leaves: it is an Æcidium; I will find out whether there is anything to be read about it.¹ De Bary has written about it but I think only about the fungus part of it:²

The Porliera in the bed is rather unhappy looking but there are two pot plants in good state & I will look to the leafstalk.³ I have got 5 or 6 Anthurium & Aroids which are put between double windows with a big tin pan filling up the whole bottom & filled with water, & if the weather only gets hot they will sprout—but they have been wretchedly cared for & are unhealthy; the gardener is very bad—⁴ Stahl ⁠⟨⁠sheet missing⁠⟩⁠⁵

the houses hospitals. I shall have plenty for the caustic experiments after I have measured them   Sachs seems interested by the caustic stopping Geotropism.⁶ Sachs seems to have completely changed his ideas about the cause of heliotropism & quite given up the idea that it is merely the shaded side growing quicker: he spoke as if these experiments of mine were hardly worth doing because it was so certain that the heliotropism does not depend on the mere difference of light on the two sides. He has lent me Wiesner’s big paper on Heliotropism 69 pp 4^to—‘Heliotropische Erscheinungen in Pflanzenreiche’, from the XXXIX B^d of the Vienna Denkschriften 1878   it can be bought.⁷ I will read it any how; Sachs doesn’t think much of it partly because it is all done by gas light. I will see what Sachs says in his last edition⁸   I was quite staggered when he spoke of “the old fashioned view of heliotropism which Wiesner still holds”

Stahl told me a little about A. B. Frank. He says he has a great respect for him & admires his work & especially likes his way of looking at the use things are to plants & not simply considering them as machines with epinasty &c like so may springs pressing them in various directions   Frank is about 40 & still a Docent, & has probably lost all chance of being a professor.⁹ He had a great dispute with Hofmeister in which he was impertinent to Hofmeister, he has also been squashed by Sachs & this has thrown him out in the struggle for life.¹⁰ The other night I went to see an Englishman named Thorne¹¹ who is lecture-assistant in the Chemical Laboratory— I went to have a lesson in the spectroscope, I had a good go at Potash & I think I shall do some drop experiments here; Sachs wont hear of it being a secretion but says it comes out a gland bearing leaf because it increases the surface & gives a delicate surface &c &c which strikes me as bosh but I dont know how to disprove it. Sachs admired my little spectroscope so much I have had to order one for him. I have been doing interesting microscoping Chara, Marchantia, Vaucheria & various funguses.¹² I went out to dinner at a Herr Merkens¹³ but it was wearisomely long— we waited for a man $\frac{1}{2}$ an hour to start with till 8 o’clock, & then after dinner sat in big circle till past 12, no one could get up & go because Sachs didn’t.

I have had very nice letters from Mother & Bessy & I will write to them: I will keep or send G’s letter. Give Ubbadubba my love & say I should a letter in bool & red [picus]. I am glad to hear that he doesn’t let Ubbady get into mischief.¹⁴ I have been cultivating Mucor spores in drops of sugary water hanging under a cover glass; they send out a long one-celled tube which grows very quick¹⁵   I have been trying to see nutation in the plane of the glass; but the floor of the laboratory shakes too much for good observations, so that the growing tip is quite jogged away from the micrometer scale. Elving the Finn knows all about pollen tube growing¹⁶   I will try whether they are negatively heliotropic

Good by dear Father | Your affec | FD