[48 and 49]

Diagram I

Nov. 4th Beta vulgaris

Fig 27 (1/3 scale no lettering)

Beta vulgaris: Fig 27 circumnutation of hypocotyl, filament fixed traversing to summit of hypocotyl, traced in darkness on horizontal glass from 8˚25' a.m to 5.30 P.m ─ filament affixed oblique obliquely to traversing to summit of hypocotyl. Tracing Movement of bend magnified 23 or 7 1/3 [2 words illeg] 1/3 of [illeg] nearly by time in figure given

[49v]

55

Chap VII

there from time immemorial, are not exempt from yellow-fever; & the Revd B. Tristram states that there are distinctly in Northern Africa which the natives are compelled annually to leave, though the negros can remain with safety.

That the immunity of the negro is in any way degree correlated with the colour of his skin is a mere conjecture; it may be connected with some difference in his blood, nervous system or other structures organs. Nevertheless from the facts above alluded to, & from some connection apparently existing between complexion & a tendency to consumption, the conjecture seemed to me not improbable. Consequently I endeavoured to ascertain, with however but little success * (47) 48, how far it hold good. The late Dr. Danielle, who lived for a long time on the West Coast of Africa, told me that he

[Descent 1: 244-5: "With the negro the immunity, as far as it is the result of acclimatisation, implies exposure during a prodigious length of time; for the aborigines of tropical America, who have resided there from time immemorial, are not exempt from yellow-fever; and the Rev. B. Tristram states, that there are districts in Northern Africa which the native inhabitants are compelled annually to leave, though the negroes can remain with safety.
That the immunity of the negro is in any degree correlated with the colour of his skin is a mere conjecture: it may be correlated with some difference in his blood, nervous system, or other tissues. Nevertheless, from the facts above alluded to, and from some connection apparently existing between complexion and a tendency to consumption, the conjecture seemed to me not improbable. Consequently I endeavoured, with but little success,48 to ascertain how far it held good. The
48 In the spring of 1862 I obtained permission from the Director-General of the Medical department of the Army, to transmit to the surgeons of the various regiments on foreign service a blank table, with the following appended remarks, but I have received no returns. "As several well-marked cases have been recorded with our domestic animals of a relation between the colour of the dermal appendages and the constitution; and it being notorious that there is some limited degree of relation between the colour of the races of man and the climate inhabited by them; the following investigation seems worth consideration. Namely, whether there is any relation in Europeans between the colour of their hair, and their liability to the diseases of tropical countries. If the surgeons of the several regiments, when stationed in unhealthy tropical districts, would be so good as first to count, as a standard of comparison, how many men, in the force whence the sick are drawn, have dark and light-coloured hair, and hair of intermediate or doubtful tints; and if a similar account were kept by the same medical gentlemen, of all the men who suffered from malarious and yellow fevers, or from dysentery, it would soon be apparent, after some thousand cases had been tabulated, whether there exists any relation between the colour of the hair and constitutional liability to tropical diseases. Perhaps no such relation would late Dr. Daniell, who had long lived on the West Coast of Africa, told me that he did not believe in any such relation."]