398 Note>i 



Colpoda cysts on it for seven years and resuscitated the organism 

 each year by moistening the shde; they afterwards encysted. I 

 think that this can scarcely be considered as a case of retained vitahty 

 for seven years, for the Colpoda obtained a new lease of life each year 

 when the slide was moistened. Nussbaum found cysts of Gastrostyla 

 vorax capable of living after two years and Maupas saw Gastrostyla 

 steinii cyst after twenty-two months drying in a watch-glass. 



These records refer to ciliates only and the longest period of retained 

 vitality, excluding Balbiani's results with Colpoda for reasons given 

 above, is two years. I have shown above that two species of Colpoda 

 have retained their vitahty for 38 years. 



I cannot find any reference to early work on these lines in the 

 case of flagellates and amoebae. Quite recently however Noc^ has 

 published a short paper dealing with latent hfe in protozoa. Some 

 tubes containing a little water and various protozoa were hermetically 

 sealed in 1908 and recently opened. There was no trace of anything 

 but encysted amoebae, some of which revived after ten days or more. 

 This proves survival for six years. A minute flagellate Oikomonas 

 termo was obtained from some rough Tonkin paper after desiccation 

 for five years. 



The retention of vitahty for a period of forty-nine years which I 

 have recorded above shows that protozoa can survive in an encysted 

 condition for a much longer time than was known from previous 

 records. 



I deal with the significance of these results in relation to the hypo- 

 thesis of protozoa acting as a limiting factor on soil bacteria in another 

 paper which I hope to publish very soon. A further paper embodying 

 the cytological work on the organisms obtained from these old soils 

 with descriptions of new species is also being prepared. 



In conclusion I desire to express my thanks to Prof. F. W. Gamble, 

 director of this laboratory, who suggested, about three years ago, 

 the desirability of examining samples of old stored soils for the presence 

 of protozoa. 



Postscript. 



Immediately after submitting the foregoing for publication I 

 obtained access to Noc's paper^, only the abstract of which I had been 



1 Noc, F., C. R. Soc. Biol. Paris, Lxxvi (1914), pp. 166-8. Absf. Jour. Roy. Mic. 

 Soc. 1914, pt. 3, p. 267. 



2 "Sur la duree de conservation de Protozoaires a I'etat humide ou dessecho " (C. R. 

 Soc. Biol. Paris, lxxvi (1914), p. 166). 



