61G DB. H. CHARLTON BASTIAN ON THE ANATOMY AND PHYSIOLOGY 



possessed by these animals. Their words are, " En resume ces mousses etaient restees 

 soixante-sept jours dans un armoire du cabinet de physique de la Faculte de Medecine 

 (du 21 juin au 27 aout), avaient subi pendant deux \o\i.xs Taction de Vair sec (du 27 au 

 29 aout), et pendant cinquante et un jours Taction du vide sec (du 29 aout au 19 

 octobre); elles etaient si completement dessichees, qu'en quatre jours d'exposition a la 

 double influence du vide et de Tacide sulfurique (du 15 au 19 octobre) elles n'avaient 

 ricn perdu de leur poids ; neanmoins vinrjt-quatre heures de simple hydration ont suffi 

 pour rendre toute leur activite aux rotiferes, aux tardigrades (Emydium, Macrobiotus), 

 et aux anguillules de ces mousses" (loc. cit. p. 319). Unfortunately other interesting 

 results anived at concerning the influence of heat upon these previously desiccated 

 animals refer to the two former varieties only, since no Anguillulida^, either living 

 or dead, were seen in these later experiments. The other animals recovered after 

 being submitted for a few moments to a dry heat of more than 212° F. According to 

 M. Davaine, however, the young of the Vibrio tritici completely lose their vitality when 

 submitted in the same way to a dry heat of IGOT. Their power of resisting low 

 temperatures is most remarkable, since he says they will recover their vital manifesta- 

 tions after being subjected to a temperature of 0° F. for eight or ten hours. 



So far as my own observations have gone at present, I find that amongst the Anguillu- 

 Udce this remarkable tenacity of life of which we have been speaking, is met with only 

 amongst the representatives of four land and freshwater genera, Tylenchus, Plectus, 

 Aphelenchus, and Cephalobus ; whilst those of all the other genera excepting Bhabditis, 

 marine as well as land and freshwater, are rather remarkable for the very opposite 

 characteristic, they being incapable of recovery even after the shortest periods of desic- 

 cation*. Very many of the species of these four genera are found in earth, lichen, 

 moss, or other situations in which they are exposed to constant vicissitudes of di'ought 

 and moisture according to ever changing meteorological conditions, and in the posses- 

 sion of this power of resisting the effects of desiccation they exhibit the most admi- 

 rable adaptation for neutralizing what would otherwise be the fatal influence of the 

 varying condition of their environment. Their whole life-history must be a strange 

 one, made up of periods of life and activity alternating with others of potential death 

 — the two states bearing no definite relation to one another as regards duration, being 

 altogether inconstant and variable, and succeeding one another under the infiuence of 

 laws so remote, as to make the successions of active and passive existence in these animals 

 almost a matter of chance. Doubtless they have a certain definite span of active existence, 

 in which to go through the stages of development and growth, and provide for the con- 



* In connexion vritli this statement I would call attention to the fact that, when water is added to these 

 animals in a state of desiccation, a deceptive appearance is produced which might mislead a hasty observer. 

 The more or less rapid imbibition of fluid into the bodies of these animals produces a few momentary contractions 

 of the body, which, though really due to purely physical causes, are sufficiently simulative of vital movements. 

 I think it must have been movements of this kind which led Otto MX-llek (Anim. Infusor.) to assert that 

 certain marine forms did possess the power of recovery after desiccation. If this is not the case, then his ob- 

 servations arc quite Ln-econcileablo with what I have myseK seen. 



