[129]

Sept 7th

Tropæolum slewed Pot —muslin Blind no dark on near side

(Plant 39 inches from window)— dark room

sides protected from light— Back open room light by cross-light

7° 48' first

8° 31' moving to L. put up muslin & lowered Blind 1/2

8° 40 to L & left

8° 51 same course pulled down whole blind

9°

9° 13 shut shutters— Back of room dimly lighted

9 23 to light & right

9 38 to Right short way — covered up whole plant in dark

10 5' from light─ do

10 25 to light & left— Used ─ do.

(10 30 now opened shutters a little but suspended towel so a mere shade more light ascertained by shadow

(for 1° 17' very almost or quite do

10 40' to light (put on 2d Towel instead of Muslin— can just see shadow of pencil

11 5' same course short distance

11 22 to right & little to light — day rather duller (still shadow fr pencil)

11 50 from light — removed 1 towel

12 22 took off towel & put muslin— (—day clouded)

12 55 to light, put on one towel & took off muslin

1 28 far from light — day very cloudy put on muslin

1 38 to light & left

2 29 to light & right

2 45 from light short way — cloudy

X 3°.3 from light & parallel — removed muslin blind (other cotton & muslin Blind still over window

3 30' to left & from light

4° 1'

4 30 to light & R. — pulled about a foot of window cotton—Blind

4 45 gone back— pulled up whole cotton Blind— evening being obscure though sky clear

5 to Left little from light— pulled down muslin blind

5 15 to Light & left

5 30 directly to light

5 45 to light & left

6 same course

6' 15 do

6 21 to light & left

6 45 to left & L

7 13 back from light

7 30 from light

8 20 to light

9° a little back from light

9 30 back from light

10. 3

10 40' P.m

8th 6° 45' a.m

[129v]

100

Ipomoea

generations, it might have been expected that the difference in height between them & the cross plants would have gone on increasing; in the later generations; but so far is this from being the case so that the difference between the two sets of plants in the 7th:, 8th: and 9th: generations taken together, is less than in the 1st and 2nd generations together. Back When, however we remember that the self-fertilised and crossed plants are all descended from the same mother-plant, — that many of the crossed plants in each generation are were related, often [7 words excised]

[Cross and self fertilisation, pp. 55-6: "As the plants which were self-fertilised in each succeeding generation necessarily became much more closely interbred in the later than in the earlier generations, it might have been expected that the difference in height between them and the crossed plants would have gone on increasing; but, so far is this from being the case, that the difference between the two sets of plants in the seventh, eighth, and ninth generations taken together is less than in the first and second generations together. When, however, we remember that the self-fertilised and crossed plants are all descended from the same mother-plant, that many of the crossed plants in each generation were related, often closely related, and that all were exposed to the same conditions, which, as we shall hereafter find, is a very important circumstance, it is not at all surprising that the difference between them should have somewhat decreased in the later generations.
* Verlot says ('Sur la Production des Variétés' 1865 page 66) that certain varieties of a closely allied plant, the Convolvulus tricolor, cannot be kept pure unless grown at a distance from all other varieties."]