and Laboratory Methods. 2089 



the thin film of water adhering to the glass. When their pseudopodia are se.en 

 to be well extended, add quickly a pipetteful of one per cent, chloretone solu- 

 tion. In fifteen seconds, or less, the amoebae will be quiet, the pseudopodia will 

 be extended, but they will not adhere to the surface of the glass. Amoebae 

 treated thus for fifteen minutes were revived in two or three minutes by the 

 addition of a pipetteful of water. A small portion of them was killed by the 

 treatment, indicating that fifteen minutes in a one per cent, solution of chlore- 

 tone is about the limit of endurance of the species tested. This rapid recovery 

 of the animals from the effect of the maximum non-fatal dose of chloretone on 

 the restoration of partially normal conditions is characteristic of its action on 

 nearly all species of animals thus far tested. 



Infusoria. — Place specimens of stentor in a watch-glass or large hollow-ground 

 cell containing about ten drops of water. Add one drop of one per cent, chlore- 

 tone solution and observe the effect, which will be evident in one or two minutes. 

 Add more chloretone solution drop by drop until the desired eft'ect is produced 

 on the general body of the cell, the larger cilia and the smaller cilia. If too 

 much chloretone is added at one time, the animals contract strongly and do not 

 quickly expand. Specimens were under observation for nearly three hours, 

 during which time twelve drops of one per cent, chloretone solution were added 

 to the original ten drops of water. Evaporation of the water and volatilization 

 of the chloretone were continually changing the liquid, but the animals were 

 under control and exhibited as much general and ciliary activity at any time as 

 suited the purpose of the study. Ciliary activity is almost normal, even when 

 the effect of the anesthetic on the body of the cell is so marked that the animal 

 fails to respond to the stimulus of a needle prick. 



The great variation in the susceptibility of different species to chloretone is 

 well shown by the following statement of the conditions observed in an experi- 

 ment with stentor about two hours after the first drop of chloretone had been 

 added, and after nine drops of one per cent, chloretone had been added to the 

 original ten drops of water which contained stentors, amoebae, and a ciliated infu- 

 sorian of undetermined species. All of these had been subjected to exactly the 

 sam§ treatment as they were in the same watch-glass ; but the stentor was gradually 

 expanding while its cilia were inactive and vacuole pulsating, amoebae were 

 active, and the infusorian was in the first stage of fission and completed the 

 process in five and one-third minutes. This differential action of the chloretone 

 is especially noticed between species, not between different normal individuals 

 of the same species. Hence, when the strength of solution has been determined 

 for a species, practically constant results will be obtained in subsequent appli- 

 cation of the same strength solution to that species. In working out the 

 strength of solution best suited to produce the desired effects by the first 

 method, it is best to place the animals in a measured quantity of water, the unit 

 of measure being a drop, a cubic centimeter, or larger unit according to the size 

 of the animals, and a careful record should be made of the amount and strength 

 of the chloretone solution added. Such a record is a safe guide for use in 

 applying the second method to the same species. 



The directions given above apply to animals of all types. In subsequent 

 issues exact formulae for the treatment of various types of animals will be given, 

 but formula; may be determined easily by any workers who can not wait for the 

 full details to be published. A. H. Cole. 



University of Chicago. 



