SR ee ae ty eee eee 7 
MARINE BIOLOGICAL STATION AT PORT ERIN. 39 
APPENDIX A. 
AN ADDRESS ON 
SOME PERIODIC CHANGES IN NATURE.* 
GIVEN BEFORE THE LIVERPOOL BIOLOGICAL SOCIETY 
By W. A. HERDMAN, F.RS. 
There is a Manx proverb meaning “ Change of work is 
rest,’ and most of us have had personal experience of the 
benefit of occasional change of occupation and of thought. 
I desire to direct your thoughts for a few minutes to some of 
the periodic changes in Nature around us. Along with a 
fundamental continuity in the series of phenomena forming 
the scientific history of the Universe, there is a certain amount 
of constant change, and to some extent periodic change, which 
is of enormous importance in connection with human affairs. 
I propose to illustrate this thesis by directing your attention 
to certain changes in Nature as they may be observed around 
Port Erm, or the Isle of Man in general. 
Tf we take up our position on the Mull Hill to the south of 
Port Erm, and look N.E. towards Ramsey, we see laid out 
before us, like a diagram, a great deal of the past history of 
this island. We see the rugged series of peaks from Bradda 
Head, along the Carnanes, the Cronk, and South Barrule to 
the great central valley, and then onwards by Greeba ana 
Injebreck to Snaefell and North Barrule—forming the back- 
bone or central axis, the oldest part of the island—in fact, 
what was the original island in early Paleozoic times. Then, 
low down on the eastern slopes of this central ‘‘ massif,” and 
possibly on the steeper west also, we may find in places traces 
* Being portions, with additions, of an unpublished Presidential Address 
delivered before the Isle of Man Natural History and Antiquarian 
Society, on April 16th, 1914. 
