SECTIONAL TRANSACTIONS.—I. 429 
18. Dr. Roserr CHampers.—Microdissection Studies on Viscosity 
Differences in the Egg during Cleavage. 
The cleavage of the egg is accompanied by a definite series of localised 
changes in the viscosity not only of the cytoplasm but also of the nucleus. 
The viscosity changes in the cytoplasm centre mainly about the two poles 
of the mitotic spindle. 
In the surface of the dividing egg the viscosity is very low, and definitely 
directed currents appear at the time of actual cleavage process.  Localised 
surface currents can be made to appear by moving the spindle with a micro- 
needle to the surface of the egg. 
Agents which inhibit cell division do so by producing generalised viscosity 
changes, and thereby eliminating the localised differences upon which the divi- 
sion of the cell depends. In this way cell division can be temporarily stopped 
by either a solidifying or liquefying agent. 
19. Dr. G. H. A. CLowsrs.—Protoplasmic Structure and Function, 
particularly as regards Physical and Chemical Conditions 
Governing Cell Division. 
20. Dr. Cart Vorctuin, Dr. J. M. Jounson, and Miss Heurn A. 
Dver.—The Quantitative Estimation of the Reducing Power of 
Normal and Cancer Tissue. 
A method is described for the estimation of the reducing power of tissues and 
biological fluid by means of various oxidation reduction indicators. The fundamental 
principles underlying the use of these indicators in biological work have been investi- 
gated, and a comparison was made of the values yielded by the purely physical 
system using the electrode and the results obtained by means of living tissue. A 
remarkable parallelism in the results of the two methods was found to exist. 
Preliminary observations have also thrown light upon the chemical character of 
‘the substance occurring in protoplasm which is responsible for the reduction of the 
indicators. 
Monday, August 11. 
21. Joint Discussion with Section B on Vitamins and the Rela- 
tion of Light to their Action. 
(a) Prof. J. C. Drummonp.—Modern Tendencies of Vitamin 
Research. 
(b) Prof. H. C. Saerman.—The Quantitative Distribution and 
Nutritional, Significance of Fat-Soluble Vitamin. 
(c) Prof. Wauter H. Eppy.—The Isolation of a Bios from Auto- 
lysed Yeast. 
(d) Prof. E. Menuansy.—The Interaction of the Anti-Rachitic 
Vitamin and other Factors of the Diet. 
(ec) Prof. W. Lasa Muter.—The Fractionation of Bios. 
Mr. G. H. W. Lucas’ fractionation of bios; last winter’s work on the 
“preparation and purification of Bios I and Bios II. Miss E. V. Eastcott’s study 
of the formation of the bioses in filtered vegetable infusions. 
: (f) Prof. W. Sremnsock.—Radiant Energy as the Anti-Rachitic 
Factor. 
my (g) Prof. H. M. Evans.—Exzistence and Characteristics of a New 
By: Vitamin necessary for Mammalian Reproduction. 
