124 



BIOLOGY OF THE PROTOZOA 



number of Protozoa by somewhat peculiar relations of the chromo- 

 somes during both vegetative and maturation divisions of the 

 nucleus. It results in the formation of double chromosomes which 

 appear to be longitudinally split. Thus in Uroleptvs mohilis the 

 8 chromosomes of the first maturation division unite in 4 pairs which 

 are split at the second maturation division, the resulting nuclei 

 having 4 single chromosomes (Fig. 21.S, p. 525). Here is undoubted 





D 



i-v; 





C~-. 



M% 



^>^^SK 









Fig. 64. — Actinospharnnn eichhornii origin of centrosome from nucleus. 

 (After Hertwi^.) 



synapsis and reduction. But in Boreria subcylindrica, Stevens 

 describes the similar union of the 4 chromosomes to form 2 during 

 the vegetative divisions and analogous conditions are evidently 

 found in the polymastigote flagellates according to the observations 

 of Kofoid and his collaborators. The significance of this apparent 

 reduction in vegetative mitosis is problematical, and the subject 

 requires further careful study (see Chapter XI for details of 

 meiosis.) 



