174 APPENDIX TO MEMOIR OF PELTIER. 



l)led, it has lost them all ; it is then no more than a very thin and diaphanotia 

 membrane in which no organ is any longer perceptible. In this state, all move- 

 ment has ceased ; the particles of the membrane itself become disintegi'ated 

 and the vorticella dissolves globule by globule ; at other times a rupture takes 

 place in a part of the membrane, the internal liquid escapes, and the animal 

 has ceased to live. 



Reproduction of wfiisoria. — It is known that among the infusona, properly 

 so called, reproduction takes place commonly by fissiparity ; they continue sep- 

 arating into two parts, and thus form new beings. This mode of reproduction 

 is so rapid that a single paramecia observed for some days divided itself four 

 times in 24 or 30 hours, producing thousands of new creatures in the lapse of a 

 few days. This generation only proceeds with activity when an exuberant 

 nourishment is supplied to these animals. Peltier, however, produced by inani- 

 tion, in a great number of animalcules, an effect analogous to that which results 

 from an excess of nutrition. 



There are species which possess a contractile dorsal vessel, in which we can 

 follow the progress of the nutritive liquid ; such are the digitated naiadse. If 

 these animals be subjected to inanition, we shall see, in proportion as the liquid 

 is impoverished, a contraction of the dorsal vessel, which is less stretched out, 

 and stops where the liquid ceases to arrive, because it has been absorbed by the 

 anterior parts. When this movement is thus arrested, there will be seen to be 

 formed, at the middle of the body, at the point where the nutritive liquid ceases 

 to arrive, and where the contraction of the vessel stops, two large absorbent 

 vesicles, which imbibe for the behoof of the posterior part. As soon as these 

 vesicles enter into action the second half of the dorsal vessel resumes its contractile 

 movements ; these contractions, be it understood, take their origin in the new 

 vesicles, and have no communication with the anterior part nor any synchro- 

 nism witli its movement. In front of these vesicles, a constriction is presently 

 fonncd, ^\hich increases by degrees, and Avhich ends by completely separating 

 the two portions, which then constitute two distinct individuals. 



The anterior portion, 1 tetter organized and better supplied with appendages 

 for alimentation, has more vivacity, more energy, than the other. If we suc- 

 ceed in preserving the drop of water seveir or eight days, the nutritive matter 

 diminishing more and more, there occurs for the two halves that which occurred 

 for the entire animal : the quantity absorbed by the anterior parts is no longer 

 sufficient for the total alimentation, and the posterior part is left in a state of 

 complete inanition. It was thus that Peltier obtained in one instance a new 

 separation into two of each of the two former halves, and eventually a new 

 separation of the two quarters proceeding from the anterior half ; the two sep- 

 arated parts of the posterior half had ceased to live before he could effect a 

 new separation. The result, therefore, w'as the formation of six individuals 

 proceeding from the separation of the parts which the dorsal vessel could no 

 longer supply with nourishment. 



Peltier has verified the same fact with regard to the pustulous kerones ; hav- 

 ing subjected these animals to protracted inanition, he perceived that, in the 

 middle of the body, an indentment was formed which went on constantly 

 increasing, and finally separated the animal into two parts ; the anterior half 

 continued to live, it appeared even to acquire new energy by the loss of the 

 posterior half of its substance, while this latter often died at once, though some- 

 times it remained alive for a certain interval. In every case, the instant of the 

 death of the individual restored to liberty and their own spontaneity the rest 

 of the globules which happened to be in its interior. Peltier observed also 

 similar peculiarities in the kidney-shaped cyclidse. 



M. Dujardin had inferred from his researches that certain animals might be 

 produced !>}'• means of lobes of their substance abandoned by them on the 

 bodies to which they attach themselves. Peltier has confirmed this idea by 



