624 Lorande Loss Woodruff. 



of the protoplasm it will however, greatly increase the motility 

 of the protoplasm and the rate of cell-division." Among the 

 electrolytes employed by Greeley are three of the salts which I 

 have used: KCl and MgSO^ with predominant cathions and 

 NaCl with the anion predominant. He found that KCl -JV ^^d 

 MgS04 3^ each exerted an inhibiting influence on the fission- 

 rate, through a coagulating of the protoplasm. Referring to these 

 salts he remarks that "the less active solutions, such as KCl and 

 MgS04 do not produce quite so dense a coagulum as the others, 

 and the reaction is considerably slower." As already stated, my 

 work with an initial stimulation of thirty minutes with KCl -f-^ 

 and MgS04 3-"-o produced a quickening of the rate of fission for 

 the first five days or more; the total result, however, for the twenty 

 days of the experiment showed an inhibiting influence. With 

 NaCl f^ Greeley found an increase in the rate and this agrees with 

 the first period of my NaCl experiment, but here again I found a 

 slowing of the rate for the total twenty days. It is impossible, 

 though, to make a direct comparison of Greeley's results with my 

 own, both on account of the great difference in the methods 

 employed and because he gives no details of the individual 

 experiments. Peters ('04) describes some experiments with KCl 

 on Stentor in which he found that initial stimulation for ten 

 minutes produced an increased division-rate for the three days 

 over which the longer experiments extended. This accords with 

 my results for the early periods of stimulation with the ^ and 

 with the Y^o solutions of this salt. 



To draw any general conclusions from my experiments with 

 salts on the division-rate of Gastrostyla, I think, would be hazar- 

 dous. Before this can be safely done it will be necessary to per- 

 form many experiments on diff'erent forms. Work on this subject 

 up to the present time, while aff"ording a nucleus of data as a basis 

 for future investigation, is too meagre and the methods employed 

 by diff^erent workers too varied to make the results at all compar- 

 able. As Towle ('04) aptly remarks: "the first step toward a 

 clearing of the haze that envelops the subject will be found, I 

 believe, when an eff^ort is made to unify the conditions under 

 which diff"erent investigators are working." From this work on 

 the Protozoa, I am persuaded that the most adequate method of 

 attacking the problem is by breeding long cultures of Infusoria 

 on a fixed diet. While this is a tedious process, it is the only way 



