PROCEEDINGS OF THE SOCIETY. 261 



Dr, Cunnington in Lake Nyasa, was represented by a specimen from 

 the last-named locality. The spine on the head was enormous compared 

 with that in other Daphnias, and the shell spine was also very long. 

 Sars stated that this species swam in a nearly horizontal position, and 

 that the movement was not jerky like most other Daphnias, but graceful 

 and uniform. Another species shown, D. carinata var. cephalata, was 

 found only in Australia, and was characterized by a truly monstrous 

 development of the thin keel running over the top and back of 

 the head. 



The mounted specimens were prepared by Mr. Rousselet, who those 

 present would be delighted to learn was slightly improved in health. 



Dr. Cropper said that he had been elaborating, in conjunction with 

 Mr. Row, of King's College, methods to concentrate dysenteric stools, 

 i.e. to get rid of as much debris as possible by certain physical and 

 chemical means, while leaving the associated amoebic cysts uninjured. 

 In addition, he had devised a method of counting entamoeba cysts in 

 stools. There were two methods in use for concentrating stools and 

 other material. The first depended entirely upon repeated centrifuga- 

 lization, and subsequent filtration of the centrifuge deposit through a 

 fine-meshed silk cloth. By this means a large quantity — roughly, 90 p.c. 

 — of the debris was removed from the stool, and the concentrate so 

 obtained would be suitable for experiments on the cultivation of 

 entamoeba, and had been used by Drs. Drew and Griffin. 



The second method was employed chiefly to assist in the diagnosis 

 of amoebic dysentery. Ether was added to an emulsion of the stool, 

 Sn a separating funnel, and on separating-out carried up a large amount 

 ■of the debris to the top. The subjacent liquid when drawn off con- 

 tained the bulk of the cysts originally present in the stool, admixed with 

 a minimum amount of debris. 



Lastly, for the enumeration of cysts in stools. Dr. Annie Porter, 

 using the hsemocytometer to count lamblia cysts, found large varia- 

 tions — from being entirely absent, to something like a thousand million 

 or more passed per day. In the case of entamoeba infections the 

 number is much smaller, and in one typical case examined ranged 

 from 10,000 to 60,000 cysts per gramme of stool, to an average of about 

 five million cysts per day. The hsemocytometer was unsuitable for count- 

 ing entamoeba cysts, because in an average infection only one cyst might 

 be present in each chamberf ul. A method had therefore been devised of 

 ruling lines on a slide ^ mm. apart, and counting with a low-power. 

 By using an emulsion of the right strength, it became a simple matter 

 to count 20 c.cm. at a time, and this has been employed as a routine 

 method. 



Drs. A. H. Drew and Una Griffin then communicated their paper 

 on the " Parasitology of Pyorrhoea alveolaris," which appears m extenso 

 in the Journal of the Society. After a short discussion, in which 

 Drs. Taylor, Rudd Leeson and Eyre, and Mr. Heron- Allen took part, 

 the President proposed from the Chair a hearty vote of thanks to the 

 authors for their contribution, which was carried by acclamation. 



