. The Journal of experimental zoology. ct moment of death is difficult todetermine in this condition, as vitality seems to remain a longwhile, and even after they have become motionless, they maysometimes be made to move again by stimulating them with acapillary rod. To determine the effect on dimensions, a large number of speci-mens were put into a ^^ NaCl solution (see table VI). TABLE VI Dimensions of adull Paramecia in ^.^ NaCl. TIME LENGTH BRE.^DTH NO. OK SPECIMENSME.^SL RED Mm. Normal at beginning 47-o 5° 3 191 .2 50 5 50 8 39-7 5° lO 39-3 5° •5 .
. The Journal of experimental zoology. ct moment of death is difficult todetermine in this condition, as vitality seems to remain a longwhile, and even after they have become motionless, they maysometimes be made to move again by stimulating them with acapillary rod. To determine the effect on dimensions, a large number of speci-mens were put into a ^^ NaCl solution (see table VI). TABLE VI Dimensions of adull Paramecia in ^.^ NaCl. TIME LENGTH BRE.^DTH NO. OK SPECIMENSME.^SL RED Mm. Normal at beginning 47-o 5° 3 191 .2 50 5 50 8 39-7 5° lO 39-3 5° •5 . 38-7 so ^5 43-4 SO 40 45-7 SO At intervals of ^ minutes, about 50 were taken out, killed andmeasured. Most of the animals died about 10 to 20 minutesafter being put into the salt, but some, more resistant than theothers, remained alive 60 minutes. The curve (Fig. i), plottedfrom these figures, is thus based on different numbers of individuals zo O Effect of Chemicals on GrozvthLENGTH 499 200 190180 V \ N ^^ ?^ WIDTH. 40 40 TIME IN MINUTES THE JOURNAL OP EXPERIMENTAL ZOOLOGY, VOL. 8 NO. 4. 500 Estabrook in different parts; it is nevertheless instructive. The changesin the form and size of Paramecium shown by the curve, are thesame as seen under the microscope. The first effect is an imme-diate decrease in the width, and at the same time, a shortening ofthe organism. Further decrease in length takes place, and then,as death approaches, the Paramecia become thicker and slightlylonger. I have designated this form of curve as the death curve, aslater work shows that its appearance is always followed by death. Adult Paramecia put into a ^^NaCl solution died in one-half to 3hours, none living in this strength longer than 3 hours. The samegeneral effects were observed as in the ^^ NaCl solution, exceptthat, extending over a longer period, they were not so marked. Adult Paramecia put into a ^ NaCl solution became thinnerfor about 20 minutes, then gradually regained
Size: 2222px × 1125px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjectzoology, bookyear1910
