468 SECTIONAL TRANSACTIONS.—B. 
to both classes of compounds (e.g. 1 : 2-dimethylphenanthrene from ztio- 
bilianic acid). : 
The testicular hormone (male sex-hormone), the action of which is 
demonstrated by the growth of the cock’s comb, is a hydroxyketone, 
CigH 3902, which contains a saturated four-ring system. Its relationship to 
the follicular hormone and to the sterols has not yet beenshown with certainty. 
Prof. E. C. Dopps.—The significance of synthetic estrogenic com- 
pounds. 
Hitherto the cestrus reaction has been regarded as a specific response to 
cestrin and its derivatives, none of which have as yet been prepared syntheti- 
cally. In collaboration with Cook it has been shown that compounds of 
widely differing chemical structure may be synthesised, capable of causing 
a full ceestrus reaction quite indistinguishable from the natural phenomenon. 
Thus, 1-keto-1 : 2 : 3 : 4-tetrahydrophenanthrene falls into this category, 
and also 9g: 10-dihydroxy-g : 10-di-n-butyl-9 : ro-dihydro-1 : 2:5 : 6-di- 
benzanthracene. In addition, it has been shown that calciferol will 
produce cestrus when injected in large quantities, as also the two carcinogenic 
hydrocarbons 1 : 2-benzpyrene and 5 : 6-cyclopenteno-1 : 2-benzanthracene. 
It would appear, therefore, that it is possible to have one molecule possessing 
pharmacological activity of two entirely different varieties. The theoretical 
importance of these observations is obviously great, since it may mean 
that the processes of cestrus-production, cancer production and vitamin-D 
activity are related in some unsuspected manner. 
AFTERNOON. 
Visit to Messrs. Boots, Nottingham. 
EVENING. 
Sectional dinner. 
Saturday, September 9. 
AFTERNOON. 
Visit to Ketton Cement Works. 
Monday, September 11. 
Discussion on The interatomic distances and forces in molecules (10.0) :— 
Dr. .N. V. Sipewick, F.R.S. 
Prof, J. E. LENNARD-JONES. 
Dr. J. M. Rospertson.—Interatomic distances in some aromatic hydro- 
carbons from a Fourier analysis of the X-ray crystal data. 
If X-ray crystal analysis can be carried far enough it yields the most 
accurate and complete information regarding interatomic distances, and has 
the great advantage of being applicable to very complicated structures with 
the same precision as to simple atomic arrangements. Owing to the 
essentially periodic structure of a crystal, we may represent the electron 
density by means of a Fourier series 
+co +00 +co 
e(x,y,2)= 2 LY XZ Apg cos 2x (px/a + gy/b + r2/c), 
—coo co 
—co — 
