452 Dr. G. C. Wallich on the Distinctive Characters, Habits, 



impelling the animal organism to sustain existence and repro- 

 duce its kind, as it does the vegetable, I beg to direct attention 

 to some singular facts, which throw light on the subject at the 

 same time that they serve the more practical purpose of denoting 

 the true characters of the phenomena to which they relate — pre- 

 mising that it will be a fitting period to discuss the question 

 of instinct when we shall have become sufficiently acquainted 

 with these lower forms to state, with any approach to accuracy, 

 the relations and limits of those vital and physical forces whereby 

 their functions are governed. 



Both Amoeba and Actinophnjs, undoubtedly possess discrimi- 

 native power in the selection of their food ; that is to say, they 

 do not incept every particle that happens to come in their way, 

 organic and inorganic alike, but, generally speaking, only such 

 substances as are best fitted for their nourishment, whilst they 

 reject those that are not so fitted. It is true that inorganic objects 

 are frequently present in the body of Amoeba, which there is 

 reason to believe have gained ingress accidentally. But, in most 

 cases, the minute size of these objects, as compared with the 

 organic food-particles associated with them, testifies to their 

 having been admitted along with the latter, and not in lieu of 

 them, or to their having been forced into the interior of the 

 plastic mass of the creature whilst moving, as it constantly does, 

 amongst organic and inorganic debris. The discriminative faculty, 

 however, is exemplified in the most remarkable manner when 

 one Amoeba comes in contact with another, or with an Actino- 

 phrys. 



Amongst the numerous instances in which I have seen Am,oeb(B 

 come into contact with each other — whether in the course of 

 their own movements or through any manipulatory efi'ort on my 

 part — it has not been my lot to witness the coalescence or fusion 

 of two individuals, which has been regarded by some observers 

 as a " zygotic " or reproductive process. On the contrary, such 

 individuals, after remaining for a time in contact, have in- 

 variably " sheered ofi"^' from each other, under circumstances 

 which proved that they were not inconvenienced by the restraint 

 to which they were subject. In like manner, I have never seen 

 the re-amalgamation of two or more portions of a divided Amoeba. 

 This is the more remarkable, since this phenomenon unquestion- 

 ably takes place in Actinophnjs ; for, although the more viscid 

 and adhesive quality of the ectosarc of the latter genus may, to 

 some extent, account for the apparent anomaly, it can hardly be 

 accepted as a satisfactory explanation of it. 



In Actinophrys, the coalescence of two individuals, which is 

 by no means of rare occurrence, has been repeatedly watched by 

 me from beginning to end ; and, with a view to ascertain whether 



