1020 REPORT—1896. 
Consideration of the theoretical bearings of these facts is deferred until they 
have been investigated in detail. 
4, A Lecture on the Geographical Distribution of Plants was delivered 
by Mr. W. T. TutsEvton-Dyer, F:R.S., C.M.G., C.I.E., Director of 
the Royal Gardens, Kew. 
TUESDAY, SEPTEMBER 22. 
The following Papers were read :— 
1, A Discussion on the Cell was opened by the reading of the following 
“Paper :— 
Some Current Problems connected with Cell-Division. 
By Professor J. BRETLAND FARMER. 
The great mass of information concerning the phenomena of cell-structure 
forms the excuse for attempting to test some of the leading hypotheses and theories 
as to the meaning of the observed facts. 
And firstly, it is necessary to exercise great care in laying the foundations of 
our knowledge, since these depend so much on material which has been subjected 
to an elaborate technical treatment before it can be appropriately examined. 
Secondly, there is a widespread tendency to generalise from a study, exhaustive 
it may be, of a few types. But there is so much variety, that, save in the broadest 
outlines, it is hardly possible to speak of a type at all. 
This is illustrated by the present position of the centrosome question. Fev 
people are agreed as to what its very nature actually is, and perhaps still fewer as 
to the part which it plays in the cell. Some regard it as the active agent in 
bringing about nuclear division, whilst others believe it to be a transient structure, 
called into existence by the forces which are at work during karyokinesis. The 
occurrence and behaviour of centrosomes during karyokinesis (nutosis) require a 
comparative treatment. Whilst it is quite possible that in the cells of some 
organisms the centrosome may possess a marked individuality, it does not there- 
fore necessarily follow that it must occur universally, or that it is concerned, as a 
principal, with the process; and this latter remark applies even to those instances 
in which it appears most prominently. Post hoc does not always imply 
propter hoc. 
The present position of the question as to the origin and nature of the achro- 
matic spindle, also, is a very uncertain one. Does the spindle arise as the result of 
an onward development of a pre-existing rudiment, or is it a new formation in the 
protoplasm? In the answer to this question, no less than in the conclusion to 
which we arrive as to the nature of the centrosome, an important principle is 
involved. It is, doubtless, simpler to admit a variety of ‘organs’ in the cell, but 
does such an admission bring us any nearer to understanding the actual processes 
of cell life ? 
Again, the chromosomes themselves present abundant difficulties, when one 
tries to arrive at a rational account which shall embrace the facts which even yet 
have been ascertained respecting them. If individuality be conceded to the chro- 
mosomes, how can this be reconciled with the facts of reduction and fertilisation ? 
It would seem that the reduction can be effected in various and radically different 
ways. But this touches very nearly their claims to the possession of that compli- 
cated structure which has been regarded as probable by some writers, and which is 
supposed by them to be intimately associated with different hereditary properties. 
