4 PRESIDENT'S ADDRESS. 



Organisms have been found showing their relations with living 

 forms, and elucidating, by the aid of comparative anatomy, 

 questions of adaptation and heredity and the solution of problems 

 attending the struggle for existence. It cannot be denied that 

 obscurities still remain. There is one question which forces 

 itself upon us. Are the characters of a species so definitely fixed 

 as to be incapable of modification ? Palaeontology and zoology 

 both evidence the marvellous elasticity even of a single species. 

 Some species of animals and plants have been traced through a 

 series of geological beds showing a continuous, gradual adaptation 

 to the conditions of their new environments, and at the same time 

 retaining their ancestral characters. This plasticity, however, 

 has its limits, beyond which it cannot pass, the species either 

 reverting to their original types or disappearing entirely. In plant- 

 life there is one incessant struggle between this plasticity on the 

 one hand and inflexibility on the other, which prevents changes 

 and preserves species. Before hastily determining a new species, 

 as so many do, it would be well to carefully trace its relations with 

 the type, and by comparing a series of intermediate forms 

 between two extremes to hesitate before severing any one cf 

 them. Some families split up into endless varieties, such as 

 brambles, roses, willows, hawkweeds, and others, and until we 

 obtain a better acquaintance with the laws of variation the clouds 

 of uncertainty must remain. The new science of biology affords 

 incontestable evidence that all life, vegetable and animal, 

 commences with a cell, containing protoplasm associated with a 

 small body, the nucleus. The difference between the plant- and 

 animal-cell consists in the former being furnished with a protect- 

 ing envelope. The presence of these two distinct organisms is 

 not a simple chemical combination, but an organic whole 

 endowed with life-possessing evolutive powers peculiar to itself. 

 Under favourable circumstances of temperature and environment 

 it carries on its work by a series of bi-sections. Some retain their 

 protoplasm and nucleus, others undergo modifications, the nucleus 

 disappears, and the cell is so transformed as to lose all traces of 

 its primitive character. In tracing the progressive stages of life 



