ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 309' 



Soatli Polar regions. Of tliese " bipolar" species the most interesting is' 

 TperhnT^s Saccamina sphserica, since it has been almost exchisively obtained 

 from stations in high latitudes, and only twice in low latitudes, in the 

 North Pacific and South Atlantic, both in deep water — in the main axes- 

 of abyssal troughs trending north and south. " In this, as in other 

 species of bipolar Foraminifera, the following fact is clearly brought 

 out : that these tiny organisms, born and bred in the richer, shallow mud- 

 zones of liigher latitudes, sink into deeper water areas when spreading 

 out through the tropical and inter-tropical seas, and again graduate into 

 shallower marine conditions as they approach the polar regions. The 

 sballow-water foraminiferal faunas of warmer latitudes, on the other 

 hand, show, broadly speaking, a restricted field." It is noted that 

 Reophax spiculifera, living side by side with R. dentaliniformis, which 

 makes a test of comparatively coarse angular sand grains, " rejects this 

 material in favour of short, siliceous sponge spicules, with which 

 awkward material it constructs fairly neat, long, funnel-shaped chambers,, 

 resembling in shape the straw covers of wine-bottles." 



Rejuvenescence in Protozoa.* — Lorande Loss Woodruflf summarizes 

 his work on rejuvenescence in Parammcium and other Infusorians. A 

 race of P. aurelia after more than eight years (1915) in culture is still 

 in a normal condition, having attained over 5250 generations without 

 conjugation or the use of artificial stimuli. The continued vitality 

 depends on the composition of the medium more than on changes in it- 

 There are periodic rises and falls in the division-rate, from which recovery 

 is self-regulated. The members of the long-lived race are able to con- 

 jugate when the proper conditions for conjugation are realized. The 

 very limited periods in which Maupas, Calkins, and others observed 

 degeneration of Paramecium have no significance for the question as to 

 whether degeneration and death are inevitable consequences of reproduc- 

 tion without conjugation. The positive fact is clear that the organisms 

 can live on indefinitely, when subjected to favourable environmental 

 conditions, without conjugation or artificial stimulation. 



Woodruff and Erdmann found that the rhythms are the physiological 

 expression of internal phenomena which involve the formation of a 

 complete new nuclear apparatus, by a definite sequence of normal 

 morphological changes that simulate conjugation. This nuclear re- 

 organization (endomixis) consists, in essence, of the gradual disintegra- 

 tion and absorption of the macronucleus in the cytoplasm. Simul- 

 taneously, a multiplication of the micronuclei is in progress. Certain of 

 the resulting micronuclei degenerate, the remaining one (or two) forming 

 the new macronuclear and micronuclear apparatus. There is an absence 

 of the third micronuclear division, which, in conjugation, forms the 

 stationary and migratory micronuclei. Obviously there is no syncaryon. 

 , The process is not a result of culture, nor peculiar to one culture. The 

 endomixis might be considered as an automatic antidote to senescence, 

 but so, perhaps, might anabolic ascendancy after a katabolic phase. A 

 demonstration of the fact that conjugation may be dispensed with 

 does not prove that conjugation has no dynamic function. The author 



* Biochemical Bull., iv. (1915) pp. 371-8. 



