110 SUMMARY OF CURRENT RESEARI HES RELATING TO 



fixed them. The most satisfactory fixative was Orth'a liquid, to which a 

 little acetic acid was added. Paraffin sections were stained with Heiden- 

 hairi's Lron-haematoxylin, Delafield's hematoxylin (3 p.c. in E«0) for 

 24 hours and then differentiated with absolute alcohol. The methods of 

 Benda and of Mann were also used, as well as the well-known tolnidin- 

 Itlue and orange G ; the action of the latter is uncertain. 



Methods of Studying Rotifera.* — G. Hirschfelder gives an account 

 of the technique employed in a study of this class. The examination 

 of living specimens was facilitated by the use of a 1 : 50,000 neutral 

 red solution. The animal, in a drop of this fluid, was placed on a slide, 

 and a coverslip with wax feet laid over it. Sufficient pressure was 

 applied to the slip to immobilise the animal without destroying it. 



In order to obtain satisfactory dead specimens, it is necessary, in 

 the first place, so to narcotise the animal that it dies fully expanded. 

 The object is put in a vessel containing 1*5 c cm. of water, and to this 

 are added two or three drops of a cocaine solution. Rousselet's mixture — 

 cocaine hydrochloride, 2 p.c, 3 parts ; alcohol, 90 p.c, 1 part ; water. 

 6 parts — is a very suitable solution. Care should be taken not to shake 

 the specimen. After about a quarter of an hour, the creature comes to 

 rest, and a drop of 1 p.c. osmic acid is added. Ten minutes later the 

 specimen is transferred to distilled water ; it is left in distilled water 

 about five hours, and then transferred to 2 p.c. formalin. The whole 

 specimen may be mounted without further treatment between two slips 

 separated by wax feet, the margins being sealed with paraffin. 



For sections, the narcotised animal may be treated with a mixture of 

 picric and chromic acids, followed by warm water and rising alcohols. 

 Ehrlich's liEematoxylin followed by orange G form the best staining 

 system. Picric and acetic acids may also be used as fixing fluid. 



Method of Studying Phagocytosis of Erythrocytes by Endothelial 

 Cells. f — W. O. Meek obtained endothelial cells from ascitic fluid from 

 cases of hepatic cirrhosis. The fluid was passed straight from the 

 siphoning tube in the sterile normal saline containing " 85 p.c. of sodium 

 citrate. The cells obtained by centrifugalizing were washed in normal 

 saline, the mass of cells being gently broken up between each washing 

 with a platinum wire. A suitable emulsion in saline was then prepared. 

 The cells were used as soon as possible after removal from the body. 



The erythrocytes employed consisted of l'O p.c. suspensions in 

 normal saline of washed red cells from a normal man and various 

 patients. The sera were obtained from normal persons and from a 

 number of hospital patients. 



Serum, erythrocytes, and endothelial cells were mixed in small 

 lengths of glass tubing sealed at one end. The open end was plugged 

 with sealing-wax, and the tubes incubated in a vertical position at 37° C. 

 for 30 minutes. The erythrocytes and cells then fall to the bottom of 

 the column, and a film is made containing a minimum of fluid. The 

 Microscope was used to ascertain whether agglutination of red cells had 

 occurred. 



* Zeitschr. wiss. Zool., xcvi. (1910) pp. 211-17. 

 t Lancet, 1910, ii. p. 1267. 



