VI PREFACE. 



nelids. We may reply upon this point, that there is not a single 

 ciliate Infusory that cannot be frightened, and that does not mani- 

 fest its fear by a rapid flight through the liquid of the preparation. 



If a drop of acetic acid be introduced beneath the glass-slide, in 

 a preparation containing quantities of Infusoria, the latter will at 

 once be seen to flee from all directions like a flock of frightened 

 aheep. 



Memory, according to M, Romanes, first begins with the 

 Echinoderms. Now, Mosbius, upon the occasion of a treatise upon 

 the Folliculina avipulla,"^ a ciliated Infusory presenting complicated 

 and interesting movements, properly remarks that every time an 

 animal repeats the same action under influence of the same excita- 

 tions, that fact proves that the animal is possessed of memory. In 

 fact, memory is one of the most elementary of psychological facts. 



Lastly, the primary instincts, according to M. Romanes, begin 

 first with the larvae of insects and with Annelids. We give, in con- 

 tradiction of this statement, the recent observations of Verworn,f 

 which reveal the existence of curious instincts among the Rhizopods. 

 The Difflugia urceolata, which inhabits a shell formed of particles 

 of sand, emits long pseudopodia which search at the bottom of the 

 water for the materials necessary to construct a new case for the 

 filial organism to which it gives birth by division. The 

 pseudopod, after having touched a particle of sand, contracts, and 

 the grain of sand, adhering to the pseudopod, is seen to pass into 

 the body of the animal.. Verworn, instead of grains of sand, 

 placed small fragments of colored glass about the animal; some 

 time afterwards, he noticed a heap of these fragments on the bot- 

 tom of the shell. He then saw a bunch of protoplasm issue from 

 the shell, representing the new Difflugia produced by division. 

 Thereupon, the materials collected by the mother-organism — the 

 fragments of colored glass — came forth from the shell and envel- 

 oped the body of the new individual in a sfaeath similar to that en- 



* Moebius, Das Flaschenthierchen , FoT^culina ampulla, 1887. 



t Verworn, ZeitschriftfUr Wissenschaftliche Zoologie, Bd. 46. H. 4. 1888. 



