In a previous paper1 one of us has summarized what is known with regard to canine piroplasmosis, and presented the results of infection experiments carried on in Cambridge with infected ticks (adult Haemaphysalis leachi Andouin) imported from South Africa. In the present paper we propose to describe and figure the parasite as observed in stained preparations, and to state what is known regarding its biology. The supply of infected ticks having unfortunately been exhausted and our last attempt at the transmission of the disease by infected blood inoculation having failed, we are obliged, for the present, to postpone a detailed description of the living parasite.

It has been estimated that 75% of typhoid epidemics are water-borne, and it is not surprising, therefore, that many attempts have been made to prove the presence of the specific bacillus in the suspected waters, although the bacteriological examination for this purpose has always been recognised as most difficult and uncertain.

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 treatment which Dr A. E. Wright has advocated of certain chronic infections, by the injection of sterilised emulsions (vaccines) of the micro-organism causing the disease, is now well known, but a brief statement of its principles may make the following observations more clear.

The disease known as equine piroplasmosis is one possessing great importance to the farming community of certain portions of Cape Colony, especially to importers, for the reason that recently imported horses sometimes develop a very acute and often fatal form of this malady. A similar disease attacks mules. The recently reported outbreak of piroplasmosis amongst donkeys in the Transvaal, if not identical, is probably very closely allied to the malady affecting horses and mules. A great mortality amongst donkeys at Lydenburg was due to piroplasmosis. Equine piroplasmosis requires further investigation, it being unknown how the disease is disseminated, although most authorities consider that the parasite is transmitted by the agency of a tick.

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.

In the preceding paper the morphology of the parasites found in the peripheral circulation and in the organs of eleven dogs experimentally infected with Canine Piroplasmosis has been described. In the following pages will be considered the morbid lesions found in hese dogs, and the proportions of the variously infected red corpuscles to one another, both in the organs and in the blood.

During the months of May and June last three batches of monkeys (Cercopithecus), making fourteen in all, were sent to me for experimental purposes. The first lot of four monkeys arrived on May 15th, and on taking their temperatures the following evening it was found that they all had fever varying from 103·8° to 106·4° F. Blood films were taken and examined the following day, but nothing was then found save a rather marked degree of polychromatophilia. That evening, May 17th, the temperature of one of the monkeys was found to be 110·4°, the animal was moribund, and died within two hours. An autopsy was made next morning, but nothing abnormal could be found. That afternoon, in examining a fresh blood preparation, a non-pigmented pear-shaped endocorpuscular body was found. This body was single, pear-shaped when first seen, and gradually changed its shape, becoming first oval and then again pear-shaped but with the thin end now at the opposite extremity. No protrusion of pseudopodia was observed.

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.

As far as can be ascertained this sporozoon has not been described before as occuring in a monkey, though several cases have been recorded in man1 and in a number of other mammals.

Having examined the blood in a number of the dogs suffering from Piroplasmosis, referred to in the previous papers, I have selected three charts to show the changes I found to take place in the blood during the progress of the disease. For the enumeration of the corpuscles the Thoma-Zeiss haemacytometer was used, and for estimating the haemoglobin, Haldane's modification of Gower's haemoglobinometer.

So much has been written concerning Piroplasmosis as it occurs in different animals in various parts of the world that one may be pardoned for directing attention to the fact that the disease exists at home and is constantly coming before the notice of the veterinarian at this time of the year.

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.

At the present time when the parasitic protozoa found in the blood are receiving great attention, it may be interest to describe a form which appears not to have been noticed hitherto.

Tr. Lewisi has been cultivated by me for nine generations, the duration of cultivation extending over a period of nine months. The culture is still alive and is now in its tenth generation. A culture of Tr. Brucei was cultivated through three generations for a period slightly exceeding eighty days. These cultural experiments, however, in no way compare, in duration of time, with those of Novy and McNeal, who have cultivated Tr. Lewisi through twenty-six generations in two years, and Tr. Brucei through twenty-seven generations in eight months. Nagana trypanosomes degenerate rapidly in cultures and then become non-virulent, but a culture of Tr. Lewisi retains its infectivity for rats for a long period. From the study of well stained preparations it has been found that the cultural forms of the rat trypanosome differ considerably from those of the adult parasite found in the blood. The chief points of difference are: (1) The trypanosome is exceedingly motile and is generally spindle-shaped. (2) The centrosome is placed anteriorly. (3) The flagellum is very long and active and has but a short intracellular course, in consequence of the position of the centrosome, from which it arises. (4) No undulating membrane is apparent. (5) The trypanosomes form colonies, which ultimately contain many thousands of individuals. The flagella of the latter are directed centrally. In rats, infected with cultures of Tr. Lewisi, the usual forms of parasite appear. The cultural forms of Tr. Brucei resemble the trypanosomes found in the blood, but are more active. The chief points of difference, viz. development of two or more vacuoles and numerous granules and sometimes the breaking up of the chromatin of the nucleus, are probably due to degeneration. The colonies, found in cultures of Tr. Brucei, consist of a comparatively small number of trypanosomes, which are arranged irregularly or with their flagella directed peripherally. The differences between cultures of Tr. Lewisi and Tr. Brucei are summarised on page 43.

In areas in which plague is present, or has recently been present, in India, as an epidemic, no definite relation has been observed between intensity of plague (apart from its persistence), and badness of sanitary condition of dwellings. On the other hand, in areas in which plague is present endemically, so far as evidence goes, very unsatisfactory sanitary conditions exist. Such areas are generally situated in mountainous countries (Garhwal, Yunnan, Beni-Cheir, Transbaikalia). The inhabitants of such places, owing to the difficulty of obtaining water for domestic purposes, are apt to be filthy both in their houses and persons. In Garhwal, Yunnan, and Beni-Cheir domesticated animals are stabled in the houses, the paucity of level area making separate provision for cattle a matter of difficulty. Stable refuse consequently is liable to accumulate in the lower floors of the houses, producing conditions favourable to the presence of swarms of fleas.

In a previous paper I referred to observations by Dr E. W. G. Masterman, on the prevalence of malaria in Jerusalem. Since that time Dr Masterman has searched various places for Anopheles in and near the city, and has found numerous larvae in the Birket Mamilla (or “Upper Pool of Gihon”) in winter, the water of which is conducted by covered conduits to Turkish baths in the city. The pool is dry in summer.

No investigations seem to have been made in recent years as to the prevalence of intestinal worms among the general population in this country. The present results are derived from the microscopical examination of the stools of 500 in-patients of Guy's Hospital. The cases were taken consecutively by beds all through the hospital, without any selection, over a period of ten months, and comprise surgical and medical as well as gynaecological and other special patients. Nearly all were inhabitants of London.

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.