KOTES AND MEMOKANDA. 69 



beginning of the century (1802), were only accurately described, 

 thirty years later, by Robert Brown (1833). Up to the present time 

 their function has been extremely obscure. The beautiful investiga- 

 tions of Strasburger (1875) have led him to the conclusion that the 

 nucleus is the seat of a central force which has a kind of polarizing 

 influence upon the protoplasm molecules, causing them to arrange 

 themselves in lines radiating outwards. Cell-division he regards as 

 primarily caused by the nucleus becoming bipolar, and the so-called 

 caryolitic figures first described by Auerbach exhibit the same 

 arrangement of the protoplasm molecules in connecting curves as in 

 the case of iron-filings about the two poles of a bar-magnet. The 

 two new centres mutually retire, and each influencing its own tract of 

 protoplasm, the cell-division is thereby ultimately effected. This is 

 but a brief account of processes which are greatly complicated in 

 actual detail, and of which it must be remarked that, while the 

 interest and beauty of the researches are beyond question, caution 

 must be exercised in receiving the mechanical speculations by which 

 Strasburger attemj)ts to explain them. He has himself shown that 

 cell-division presents the same phenomena in the animal kingdom, a 

 result which has been confirmed by numerous observers, amongst 

 whom I may content myself with mentioning one of our own number, 

 Mr. F. Balfour. Strasburger further points out that this affords an 

 argimient for the commimity of descent in animal and vegetable cells ; 

 he regards free cell-division as derivable from ordinary cell-division 

 by the suppression of certain stages." 



The address then deals with the discoveries made during the last 

 five years in physiological botany, more particularly by Mr. Darwin 

 and Dr. Burden Sanderson. 



Lichens, Bacteria, Bacillus Organisms, and the Lowest Forms of 

 Life. — Referring to these subjects. Sir Joseph Hooker said, " In 

 morphological botany attention has been especially directed of late 

 to the complete life-history of the lower order of cryptogams, since 

 this is seen to be more and more an indispensable preliminary to any 

 attempt at their correct classification. 



The remarkable theory of Schwendener, now ten years old, 

 astonished botanists by boldly sweeping away the claims to auto- 

 nomous recognition of a whole group of highly characteristic 

 organisms— the lichens — and by affirming that these consist of 

 ascomycetal fungi united in a commensal existence with algfe. The 

 controversial literature and renewed investigations which this theory 

 has given rise to is now very considerable. But the advocates of the 

 Schwendenerian view have gradually won their ground, and the 

 success which has attended the experiments of Stahl in taking up the 

 challenge of Schwendener's opponents, and manufacturing such 

 lichens as Endocarpon and Thelidium, by the juxtaposition of the 

 appropriate algae and fungi, may almost be regarded as deciding the 

 question. Sachs, in the last edition of his ' Lehrbuch,' has carried 

 out completely the principle of classification of algae, first suggested 

 by Cohn, and has proposed one for the remaining thallophytes, which 

 disregards their division into fungi and algae. He looks upon the 



