ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 367 



life varies with the individual and according to the rigour of the starva- 

 tion. It is on an average 5 to 7 days, but, in rare cases, it may he pro- 

 longed for 20 days. On the fourth day of starvation the Parammium 

 begins to become deformed, first Bhowing a dorso-ventral flattening, and 

 finally taking the form of a crescent, with the convexity dorsal. There 

 is a progressive diminution in size, especially as regards breadth, so that 

 the animal becomes relatively longer than in the normal state. It dies 

 when it has lost about half its original volume. The ectoplasm under- 

 goes no change, and the cilia and trichocysts remain intact, but the 

 endoplasm gradually loses all its digestive vacuoles and some of its 

 crystals, thus becoming extremely transparent. The macronucleus in- 

 creases in size, elongates, and divides into two halves, which move away 

 from each other. This breaking up has no relation to amitotic division, 

 and its products persist till death without undergoing digestion. The 

 micronucleus moves away from the macronucleus, but, as a rule, it 

 undergoes no alteration in form or structure, whatever may be the 

 duration of life. Individuals in which starvation is not pushed to an 

 extreme are able to recuperate all their normal characters if they are 

 placed in a medium of weak but gradually improving nutritive capacity. 

 Death is preceded by a progressive slowing of all the functions, including 

 the play of the cilia and the contractions of the vacuoles. The degenera- 

 tive process in a starved Paramecium is thus, in a general way, similar 

 to that which takes place in individuals that have been poisoned by the 

 excretions of butyric or other putrefactive bacteria. The vacuolization 

 of the endoplasm, which has been attributed by some authors to inanition, 

 is apparently a result of the chemical action of the ammoniacal products 

 always present in infusions in which putrefaction is going on. 



Two Thousand Generations of Paramoecium.* — Following up his 

 earlier papers on the life-cycle of Paramo&cium, L. L. Woodruff describes 

 an attempt to eliminate the cyclical character of the rate of production 

 by constantlv subjecting the Infusoria to a varied environment. The 

 pedigree culture was started with a " wild " Paramecium aurelia, and 

 when it had divided twice the four individuals were isolated on other 

 slides. A specimen of each of these four lines was isolated daily, so as 

 to preclude the possibility of conjugation between sister-cells. The 

 culture medium was made from materials collected practically at random, 

 the infusion being thoroughly boiled to prevent contamination by wild 

 individuals. In the 41 months during which the culture has been under 

 observation it has not completed a " cycle," though there has been a 

 rhythmic rise and fall in the division-rate. The rate of fission is graphi- 

 cally plotted in a series of charts. The author believes that this culture 

 shows clearly that P. aurelia., under suitable culture conditions, has the 

 power of unlimited reproduction by division, without conjugation or 

 artificial stimulation. 



Leptomonad in Euphorbias.!— G. Bouet and E. Roubaud confirm 

 Lafont*s discovery of Leptomanas davidi in Euphorbia. The infection is 

 local ; it does not seem to last ; it does not seem to have any bad effects. 

 They were led to regard a small Hemipteron, Dieuches humilis, as the 



* Arch. f. Protistenkunde,xxi. (1911) pp. 264-6. 

 + C.R. Soc. Biol. Paris, lxx. (1911) pp. 55-7 (1 fig.). 



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