The Journal of experimental zoology . eding rhythm. In the ascending cycle also, theslowest rate in each rhythm is greater than the slowest rate of thepreceding rhythm. So far we have not considered the long trend of the division-rate, which I regard as the cycle as I believe that this is directlycomparable with the cycle of Calkinss Paramcecium cycle obviously extends over more generations in Oxytrichathan in Paramoecium though in both cases it is a variable numberboth in the same culture and in different cultures of the samespecies. Maupass rather definite limits to the life-cyc
The Journal of experimental zoology . eding rhythm. In the ascending cycle also, theslowest rate in each rhythm is greater than the slowest rate of thepreceding rhythm. So far we have not considered the long trend of the division-rate, which I regard as the cycle as I believe that this is directlycomparable with the cycle of Calkinss Paramcecium cycle obviously extends over more generations in Oxytrichathan in Paramoecium though in both cases it is a variable numberboth in the same culture and in different cultures of the samespecies. Maupass rather definite limits to the life-cycle are notsubstantiated by this work as will be readily seen by comparingthe various culture-curves. It must be borne in mind, however,that neither Maupass chief cultures nor my own were startedwith ex-conjugants, and therefore the number of generations doesnot afford a just basis of comparison, since they indicate merelythe number of bipartitions since the culture began and in no sense The Life-History of Hypotrichous Infusoria. 603. Dec. Jan. Februar7 March 1902 1903 Diagram VII. April Sections of the culture-curves of Oxytricha A, and B, and Pieurotricba A, and B, together withthe temperature curve for the same period (December lo, 1902 to May 9, 1903), showing the corre-spondence of the rhythms of the division-rate with the fluctuations in temperature. 6o4 Lorande Loss Woodruff. the age of the culture with reference to the last conjugationperiod. The number of generations from the recovery of myOxytricha A-culture to its extinction gives the number of divisionsin a cycle of an artificially stimulated line, but it remains to beshoMm that this is directly comparable to rejuvenescence byconjugation. Joukowsky carried a series of Pleurotricha lanceolata through458 generations and found no signs of degeneration, and he sug-gested that degeneration depends not on the number of divisionsonly, but on the rapidity w^ith which they succeed each conclusion, on a priori grou
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