[141]

T. repens Sept. 30 terminal leaflet N.E window— vertical glass

Trifolium repens

8° 35 — petiole fixed within inch of leaflets

8 55' down to light

9 18' do do

9° 35' do do

10 24' do but less steep by & to light

11° 3' down & from light} day brighter, few clouds

11 28' just begun to rise — do — do

11 45 down & parallel

[slip of paper pasted on:]

12° 3' still down

12° 48' still falling a little & to light

2° still going down

2° 50 from light

3° 15' to light, yet rather cloudy

4° great rise

5° no dot risen above glass

(Used)

7° 13' P.m. to middle of chalk on spike. Leaf fully asleep

7 55 much lower down

8 45' still lower

9 40' — a little way down

10 25 a little risen.

Oct 1' 6° 50' 45+ still asleep but greatly risen since last night

7° 5 fallen

7° 25' do

8° do

(24.A

(Ch. 8) To sum up on the means through which, as far as we can judge, sexual selection has led to the developments of the secondary sexual characters which are characteristic of so many animals in all classes. It has been shown that the largest number of vigorous offspring will probably be reared from the pairing of the strongest & best-armed males which have been victorious over conquered other males of with the strongest & best-armed most vigorous & best nourished

[slip of paper pasted on:] females, which will be the first to breed in the spring. Such females, if instead of at once accepting the victorious males, they should they select the more attractive but & at the same time more vigorous males, instead of the most victorious will nevertheless rear more offspring that the retarded females which will commonly pair with [2 words illeg] less vigorous males & less attractive males.

So conversely it will be if the more vigorous males select the more attractive females &

at the same healthy & vigorous females; & thus will especially hold good if the male defends the female & [illeg] in providing for the young.

[Descent 1: 271: "To sum up on the means through which, as far as we can judge, sexual selection has led to the development of secondary sexual characters. It has been shewn that the largest number of vigorous offspring will be reared from the pairing of the strongest and best-armed males, which have conquered other males, with the most vigorous and best-nourished females, which are the first to breed in the spring. Such females, if they select the more attractive, and at the same time vigorous, males, will rear a larger number of offspring than the retarded females, which must pair with the less vigorous and less attractive males. So it will be if the more vigorous males select the more attractive and at the same time healthy and vigorous females; and this will especially hold good if the male defends the female, and aids in providing food for the young."]

[142]

Trifolium repens— plant & leaf in same position but I fixed mark in pot

Oct 1

8° 5'

9° 5 down

9° 27' rising a little & fog gone, so sky brighter

10° 13' little way to the light}

10 33' down & from little from light} uniform high cloudy sky

10 54' do — do — do

11. 25'

12° — same direction a little from light yet sky rather brighter

12° 18 do do do do}

12. 45' same spot} Diagram 2

1° a trifle to the light

1. 40' up & parallel

{2° do do}

{2° 20 — same spot} movement very slow (Used)

3° rising up—

3° rising up—

4° do

4° 30' now rising much more quickly

4° 54'

5. 20' high up

5. 33' almost up to top of glass going to sleep, but not nearly fully asleep.

Oct 2d 6. 55 not fully awake to left upright

7° 30' + (measurement oblique)

8°— down

44 47

Chap. 8

in both cases. transmitted through the opposite sex.*(18) 23

Although we are thus so ignorant in most cases, yet one rule seems often to hold good, namely that variations which occur first appeared in either sex, at the late period of life, generally tend to be exclusively transferred become developed in transf to the same sex alone; whilst variations which occur first appeared early in life generally tend to be transmitted to developed in both sexes. I am, however, far from supposing that this is the sole determining cause. As I have not elsewhere discussed this subject in my previous works, and as it has an important bearing on sexual selection, I must here enter on into considerable details.

It appears in itself in some degree probable that any new character arising appearing at an early age, would tend to be  equally inherited by both sexes, for the sexes do not differ much in constitution before the power of reproduction has been gained. On the other hand, when after this power has been gained and the two sexes have come to differ much in constitution, the gemmules (if I may again use the language of Pangenesis) which are cast of, according to the hypothesis of pangenesis, from any each varying part in the one sex would be much less likely to have possess the proper affinities for for uniting with the tissues of the opposite sex, and thus becoming developed.) than at an earlier age, when the

[Descent 1: 285-6: "Although we are thus ignorant, two rules often hold good, namely that variations which first appear in either sex at a late period of life, tend to be developed in the same sex alone; whilst variations which first appear early in life in either sex tend to be developed in both sexes. I am, however, far from supposing that this is the sole determining cause. As I have not elsewhere discussed this subject, and as it has an important bearing on sexual selection, I must here enter into lengthy and somewhat intricate details.
It is in itself probable that any character appearing at an early age would tend to be inherited equally by both sexes, for the sexes do not differ much in constitution, before the power of reproduction is gained. On the other hand, after this power has been gained and the sexes have come to differ in constitution, the gemmules (if I may again use the language of pangenesis) which are cast off from each varying part in the one sex would be much more likely to possess the proper affinities for uniting with the tissues of the same sex, and thus becoming developed, than with those of the opposite sex."]