Nov. 1S94.] BOTANICAL SOCIETY OF EDINBUKGH. 275 



The PiiESiDENT (Professor F. 0. Bower) delivered the 

 following address : — 



In selecting a subject on which to address the Society, 

 I have thought that I could not do better than direct your 

 attention to certain matters connected with the minute struc- 

 ture of the cell and nucleus, in which great advances have 

 recently been made in our knowledge ; and these at the 

 present time especially demand our attention, since the 

 questions do not now merely relate to minutia) of structure, 

 but are acquiring a wide theoretical bearing upon some of 

 the largest of our morphological ideas — even upon alter- 

 nation of generations itself, which is one of the broadest 

 morphological conceptions we possess. 



Perhaps no generalisation focussed attention more 

 definitely on the nucleus than that of Strasburger, that free 

 midair formation docs not taJce ijlacc. In the earlier periods 

 of nuclear investigation, it was given out that new nuclei 

 might be formed by a process of aggregation of nuclear 

 matter derived from the cytoplasm round certain points. 

 Such formation of fresh nuclei was styled free nuclear 

 formation. As long as such a view was entertained, the 

 nucleus would possess, as regards its origin, no greater 

 interest than oil-globules or starch-grains. But closer 

 observation showed that fresh nuclei are always derived 

 from pre-existent nuclei. Naturally this suggested the 

 intimate connection between nuclei and heredity. The 

 conception of the origin of nuclei by lineal descent from a 

 remote ancestry, naturally connected itself with that of the 

 similar origin of the living organisms in which they are 

 found ; and the idea thus arose that the nucleus may be 

 the liearer of the hereditary qualities transmitted to off- 

 spring. 



Xow we know that coalescence of nuclei is an essential 

 feature in fertilisation ; and it has been shown by Van 

 Beneden that the number of chromosomes in the two 

 coalescing nuclei is the same : the resulting nucleus of the 

 zygote will therefore acquire twice that number of chromo- 

 somes — an equivalent quantum from each. Are we then 

 to imagine that each succeeding generation will have twice 

 as many chromosomes in its nuclei as the preceding ? 



