343 



MR. HAROLD WAQER'S ADDRESS, 



The Presidential Address to the Botanical Section of the British 

 Association was delivered at Johannesburg-, and dealt with some 

 problems of cell structure and physiolog-y. In the course of his 

 remarks the President (Mr. H. Wag-er, F.R. S.) pointed out that 

 the discovery that all living" organisms are composed of micro- 

 scopic vital units, called cells, in which the living substance — the 

 protoplasm — resides, had paved the way to a clearer under- 

 standing- of the complicated processes which are at work in the 

 growth and reproduction both of plants and animals. The 

 structure of the cell has a definite relation to its physiological 

 activities. The essential constituent of a cell is the protoplasm. 

 This is differentiated into a semi-fluid substance known as the 

 cytoplasm and a central denser substance known as the nucleus. 

 The structure of the nucleus is extremely complicated ; it exists 

 in the form of a g-ranular network, and contains a substance, 

 characterised chemically by the presence of phosphorus, which 

 represents probably the highest point in the development of 

 living- matter. The nucleus is the centre of activity in the cell 

 and governs all its vital functions. In the processes of growth 

 and reproduction it gives rise to a number of deeply stainable 

 structures — the chromosomes — which are the carriers of the 

 hereditary tendencies of the organism and are therefore inti- 

 mately bound up with the phenomena of heredity and variation. 

 It has been sug-gested that an organism may be regarded as 

 a colony of independent units (cells) by the co-operation of 

 which it exists as an individual, but this is not correct. The 

 cell cannot be reg-arded as an independent unity working- merely 

 in association with other cells ; the various functions performed 

 by it are no doubt dependent upon its own activity, but the 

 exercise of these functions is g-overned by the org-anism as 

 a whole, and in none of the hig-her plant or animals can the 

 cell have an independent existence. 



Many attempts have been made to show that the apparently 

 formless, semi-viscid cytoplasm possesses, like the nucleus, 

 a definite structure related to the various functions which it 

 performs. The most noted of these is the hypothesis put for- 

 ward by Butschli that the cytoplasm has a foam structure. 

 This hypothesis and others is discussed in the address, and the 

 general conclusion is arrived at that it is more in accordance 

 with the facts we know regarding- the cytoplasm that it should 

 be considered as a homogeneous semi-fluid substance, in which 



1905 November i. 



