[1 and 2]

Ampelopsis July 10th Short, straightening of

Tracing I

[2v]

35

Introduction

were exposed to slightly different conditions as the seasons varied, and as they were raised at different periods. But in other respects all were treated alike, being grown in pots, in the same artificially prepared soil, watched being watched at the same time, and kept in the same greenhouse or hothouse. They were therefore not exposed during successive years to such great vicissitudes of climate as are plants growing out of doors.

(open)

On some apparent and real causes of error in my experiments.─ it has been objected to such experiments as mine, that covering plants with a net, although only for a short time whilst in flower, may affect their health and fertility. I have seen no such an effect except in one instance with a Myosotis, and the covering may then not have been the real cause of injury. But even if the net were slightly injurious, and certainly it was not so in any high degree, as I could