202 
Proceedings of the Royal Society 
suggested as to the identity of the pituri alkaloid with the alka- 
loid of tobacco ; hut it would appear that some observers have 
noted dilatation of the pupil as a result of the direct application of 
nicotia to the eye-ball. 
It was pointed out as a remarkable fact that the aborigines of 
Australia should have discovered, and when discovered, placed a 
high value upon the action of a substance closely resembling in its 
composition and effects the tobacco so well known to, and so highly 
appreciated by, millions of the human race. 
2. On the Structure and Affinities of the Platisomidse. 
By Dr B. H. Traquair. 
3. Note on the Probability that a Marriage entered into by a 
Man above the Age of 40 will be Fruitful. By Thomas 
Bond Sprague, M.A., F.B.S.E. (Plate XIY.) 
When it is desired to disentail a landed estate, it is necessary 
for the heir in possession, after obtaining the consent of the first 
substitute heir, to pay to the second and third heirs the esti- 
mated value of their expectancy or interest in the estate. In the 
calculations that have to be made for the purpose of ascertaining 
this ^alue, the actuary has often to take into account not only 
the probabilities of life, but the probabilities of marriage and of 
leaving issue. The heir in possession may be unmarried, in which 
case he may marry at some future time, and leave a child who 
would inherit the estate to the exclusion of the subsequent heirs ; 
or the heir in possession may be married but have no children, and 
the probabilities then to be estimated are (1) that his present wife 
will have a child at some future time, and (2) that she will die 
before her husband, that he will then marry a second time, and 
have issue by his second marriage. Similar contingencies may 
occur with regard to the first substitute heir. The theory of the 
calculation of life contingencies is well understood ; and much has 
been done in the way of accumulating marriage statistics and cal- 
culating the probability that a man of any age, bachelor or widower, 
will marry at some future time; but little, if anything, has been 
