412 ZOOLOGY. 



central part of the nucleo-centrosome and then split longi- 

 tudinally like the chromosomes of Metazoan cells. Dan- 

 geard, on the other hand, considers that these threads are not 

 separate chromosomes, but lengths of a continuous thread 

 forming a skein, and that all the threads of the skein are 

 broken transversely at the moment of division. The 

 character of the mitosis is sufficiently indicated by fig. 203, H. 

 This special kind of mitosis is distinguished by the term 

 haplomitosis (haplos, simple; mitosis, weaving). 



12. Classification. Euglena is generally considered to 

 belong to the animal kingdom in spite of the presence of 

 chlorophyll. The occurrence of the flagellum and the 

 active motion in themselves prove nothing, for flagellate 

 cells occur in the life histories of many algae. But the 

 absence of cellulose and the presence of the contractile 

 vacuole are animal characters, and Euglena seems to be 

 allied to many forms which have no chlorophyll and have 

 a holozoic mode of nutrition. Such forms are placed in 

 the class Mastigophora or Flagellata, distinguished from 

 the Ciliata, of which Paramecium is an example, from the 

 Rhizopoda, illustrated by Amoeba, and from the Sporozoa, 

 which include Monocystis and Coccidium. 



