114 PROTOZOOLOGY 



position (Spirostomiim) or swim to the anode (Paramecium, 

 Stentor, etc.). Of flagellates, Verworn noticed that Trachelo- 

 monas and Peridinium moved to the cathode, while Chilomonas 

 Cryptomonas, and Polytomella, swam to the anode. 



Regeneration 



The power of regenerating the lost parts of the body is char- 

 acteristic of all Protozoa from simple forms to those with highly 

 complex organization, as shown by observations of numerous 

 investigators. The general procedure of the experiment is to cut 

 the body of a protozoan into two or more parts and observe how 

 far each part regenerates. It is now well established that only the 

 parts which contain the whole or part of the nucleus are able to 

 regenerate completely under favorable circumstances. A re- 

 markably small portion of a protozoan is known to regenerate 

 completely. For example, Sokoloff found 1/53-1/69 of Spiro- 

 stomum and 1/70-1/75 of Dileptus were able to regenerate. Ac- 

 cording to Philps, portions down to 1/80 of an amoeba are able 

 to regenerate. Burnside (1929) cut 27 specimens of Stentor 

 coeruleus belonging to a single clone, into two or more parts in 

 such a way that some of the pieces contained a large portion of 

 the nucleus while others a small portion. These fragments re- 

 generated and multiplied, giving rise to 268 individuals. No 

 dimensional differences resulted from the different amounts of 

 nuclear material present in the cut specimens. Apparently regula- 

 tory processes took place and in all cases normal size was restored, 

 no matter what was the amount of the nuclear material in an- 

 cestral pieces. Thus, in this ciliate, biotypes of diverse size are 

 not produced by causing inequalities in the proportions of nuclear 

 material in different individuals. 



The parts which do not contain nuclear material, may continue 

 to show certain activities, such as locomotion, contraction of the 

 contractile vacuole, etc., for some time. For example, Penard 

 observed enucleated amoebae lived eight days, Stole and Gruber 

 found amoebae without nuclear material were able to live up to 

 30 days, and enucleated pieces of A. verrucosa were seen to remain 

 alive for 20 to 25 days (Grosse-Allermann). 



At the time of reproduction of all Protozoa, the various organel- 

 lae, such as cilia, flagella, cytostome, contractile vacuole, etc., 

 are completely regenerated before the separation of body occurs. 



