As the result of several years of clinical and pathological experience of beri-beri in the Malay peninsula and other parts of the Far East I have been forced to the conclusion that beri-beri is an acute infectious disease with a definite primary lesion.

The extreme diversity of opinion as to the identity of the Klebs-Loeffler bacillus and the bacillus of Hofmann, and the importance of the subject from the public health standpoint, make it desirable to bring forward any facts which may assist in arriving at a solution of the problem.

Inspection by a sanitary expert of all tidal rivers where oysters or other shell-fish are laid, or found, is of the highest importance, but it may frequently, with advantage, be supplemented by a bacteriological investigation.

1. The ordinary method of calculating the birth-rate does not distinguish between the influence of fertility and of variations in conditions of the population as to age and marriage.

2. In ascertaining the true meaning of the great reduction of the birth-rate which has occured in the last 25 years it is necessary to have means for distinguishing between the accidental and the intrinsic causes of change.

3. A step in the right direction is made when the legitimate births are stated in terms of the married women at child-bearing ages, and the illegitimate births in terms of the unmarried women of the same ages.

4. This method fails to correct for the differences of fertility of the various ages comprised in the age-period 15–45.

5. By calculating standard fertility-rates for given populations McLean overcame the above difficulty, and was thus able to compare experiences of a given community at different times with the standard.

6. In this paper it is shown that by continuing the above process and obtaining corrected fertility-rates, the fertility-rates of different communities can be made directly comparable.

7. The inconveniences of this new and unfamiliar method, and the necessity involved in it of calculating the crude as well as the corrected fertility-rate in every instance, indicate the desirability of obtaining a factor for each community which throughout an entire intercensal period can be applied to the crude birth-rate of that community.

8. The desirability of such a factor is increased by the fact that the method of corrected fertility-rates does not take into account the proportion of married women in each population.

9. In this paper a method is described of obtaining factors, which, when applied to the readily available crude birth-rates, correct completely both for the varying proportion of married women in compared populations and for the varying fertility at different periods of married life.

10. The practical bearings of these corrected birth-rates will be discussed in a later paper.

The following is an addendum to a paper which appeared in the last number of this Journal.

The primary object of the paper was to give working formulae for the construction of a shortened Life-Table, set forth with sufficient clearness to enable them to be practically used by anyone who understands ordinary arithmetic and the use of logarithms, without any necessary comprehension of the principles of the differential or of the integral calculus, by means of which the formulae have been deduced.

The following notes on trypanosomes which I have observed in certain mammals, birds, and goldfish obtained in the neighbourhood of Elstree in Hertfordshire appear worthy of publication, for the reason that our knowledge regarding the geographical distribution of trypanosomes is far from complete. No description has as yet been given of the trypanosomes found in bats by various observers, and a species encountered by me in the mole is, I believe, new.

Many years ago while making in the laboratory of the late Prof. Carnelley in Dundee, by Pettenkofer's method, a series of Carbonic Acid determinations, in which turmeric paper was used as the indicator, I observed that the last few brown rings made on the paper as the solution approached neutralization showed a tendency to become decolorized in a relatively short space of time, the final ones being seen to vanish even as one looked at them. This at the time—and subsequent observation has confirmed the truth of the conclusion—was ascribed to the CO2 of the air rapidly neutralizing the solution of baryta, which getting more and more dilute as the solution of oxalic acid was gradually added, finally reached a degree of dilution that was all but instantly neutralized by the amount of CO2 present in an ordinary atmosphere. Even then I came to the conclusion that the phenomenon depended on a principle which might probably be made the basis of a rapid method of estimating the amount of CO2 in air generally, but it is only recently that I have had time to adjust the details of the method which I now propose. It will readily be understood that a long series of experiments other than those of which the results are now recorded were carried out before finality was reached on many points of the method. These need not be detailed here, though some of them will be alluded to as occasion arises. It may be stated that the method has been found to give results which approximate to the truth—at least as tested by Pettenkofer's method—much more closely than was at first anticipated.

DURING the last six years (1899—1904) some fifteen thousand examinations of material from throats for the diphtheria bacillus have been made at the Lister Institute. The localities from which this material has been derived have naturally been widespread and varied; much of the work however has been done for local authorities in and near London, and the sources of origin of the major part of the material have not varied very much during the whole period under review.