4IO SECTIONAL TRANSACTIONS.— B, C. 



in the 21 -position leads to a compound (XII) which occurs naturally, is 

 known as progesterone, and is the active principle of the corpus luteum. 



OH 

 /^! ^CO-CH, ( V ^CH-CH,OH 



o^\/\/ 



(XII) Progesterone (XIII) 



This compound, however, shows no cortin-activity, which proves that the 

 hydroxy-group in the side chain is essential. Compound (XIII) has also 

 been synthesised, and this compound and also compound (IX) show no 

 noticeable activity. More exact knowledge as to the relation between 

 chemical constitution and biological activity must await the syntheses of 

 further closely related compounds and of more detailed biological studies. 



Prof. A. R. Todd. — Vitamin B^ and its synthetic analogues (11.55). 



The existence of an antineuritic factor (vitamin Bj, aneurin) has been 

 known for almost forty years, but its isolation in a pure condition from rice 

 polishings was only achieved in 1926. The vitamin, usually isolated as 

 its crystalline chloride hydrochloride C12H18ON4SCI2 has been the subject 

 of much chemical investigation leading to the elucidation of its structure 

 and its complete synthesis, the latter being realised independently by 

 German, American, and British workers. As a result of these syntheses 

 the vitamin is now prepared commercially and has become available for 

 clinical and nutritional purposes. With a view to determining the struc- 

 tural features necessary for vitamin activity a number of synthetic analogues 

 have been prepared. The results of this work indicate a remarkable struc- 

 tural specificity, for, apart from alteration in the nature and position of the 

 alkyl substituent on the pyrimidine nucleus, any change in the vitamin 

 molecule destroys the physiological action almost completely. Although 

 it is not yet possible to state with certainty the exact function of vitamin B^ 

 in plants and animals, it is clear that it plays an important r61e as part of an 

 enzyme system in carbohydrate metabolism. 



General Discussion (12.15). 



Afternoon. 

 Visit to the University Departments of Biochemistry and Parasitology. 



SECTION C— GEOLOGY. 



Thursday, August 18. 



Prof. O. T. Jones, F.R.S. — The geology of the Cambridge district (lo.o). 



Joint Discussion with Section K (Botany) on The post-glacial history of 

 the Fenlands (11. 15). 



Dr. H. Godwin. — Introduction. 



The post-glacial deposits of the Fenland consist chiefly of peat beds on 

 the landward side and brackish water or marine silts and clays on the 



