18 ACTION OF AUXETICS AND KINETICS 



type of nuclear division that the probability of 

 specific distinction can be inferred. The more 

 advanced the knowledge of these organisms be- 

 comes, the more difficult it is to determine the 

 characters on which subdivision into species should 

 be made, and in all probability the species gradually 

 merge into each other. The amoeba under con- 

 sideration exhibits minor differences in several 

 respects from types already described in the litera- 

 ture of the subject, and, in order to distinguish 

 it, the name Amoeba ostrea is provisionally sug- 

 gested for this variety, from the fact that its 

 common form when in a resting condition resembles 

 that of an oyster (fig. 1). In general appearance 

 and common mode of nuclear division, which is 

 a form of promitosis, this amoeba most nearly 

 resembles a new species discovered by Swellen- 

 grebel and named by him Amoeba salteti. It 

 appears to be a fresh-water species belonging to 

 the genus Vahlkampfia, and is non-pathogenic to 

 guinea-pigs, dogs, and man. 



Special Methods of Examination. A description 

 is given in detail of the technique employed in the 

 routine examination of amcebas and their cysts, 

 under different conditions of environment, in the 

 hope that it may be of use to those who wish to 

 take up the jelly method in the study of other 

 protozoa. At the outset we discarded the employ- 

 ment of slope cultures in test-tubes as we were not 

 always able to recognise and to recover amoebae 

 from them under the artificial conditions to w r hich 

 they were often subjected. We found small Petri 

 dishes (two inches in diameter) preferable to the 

 larger ones, as they are more easily handled and can 



