278 



REDUCTIOX OF Til!': C//A'O.UOSOMES 



earlier- divisions the number is ajii^roximatel)' double this (8-9). This 

 observation makes it nearl\- eertain that a numerical reduction of 

 chromosomes occurs in the Protozoa in a manner similar to that of 

 the higher forms ; but the reduction here appears to be deferred until 



Jl 



B 



C 



Fig. 138. — Conjugation and formation of the polar bodies in Adiuoplirys. [SCHAUUINN.] 

 A. Union of the gametes; first polar spindle. B. Fusion of the cell-bodies; a single polar 

 body near the periphery of each. C. Fusion of the nuclei. 



the final division. In the gregarines VVolters ('91) has observed the 

 formation of an actual polar body as a small cell segmented off from 

 each of the two conjugating animals soon after their union ; but the 

 __ number of chromo- 



somes was not deter- 

 mined. S c h a u d i n n 

 ('96, 2) has observed a 

 like process in Acti- 

 nophrys, each of the 



gametes 



segmentmg 



off a single polar body, 

 after which the germ- 

 nuclei fuse (Fig. 138). 

 It is possible, as R. 

 Hertwig ('98) points 

 out, that in both these 

 forms a second polar 

 body may have been 

 overlooked, owing per- 

 haps to its rapid dis- 



Pig. i3p. — Formation of polar bodies and conjugation in HltegratlOn. '\x\. ActlHO- 



Actinosph<Brium. [R. Hertvvig.] sp/icerim/i, according to 



A. Two gametes ("secondary cysts"), resulting from the ^ Hertwio" C'qS ^ the 

 division of a "primary cyst"; second maturation-spindle in » V V*-* A ^ 



each; first polar body shown in the right gamete, at/. B. Both nuclcUS of each gamete 

 polar bodies yi/2) formed in the right gamete the second Ji^-jdes t^^i^e in rapid 

 one forming m the left gamete. C. Subsequent fusion of the ^ 



gametes; nuclei uniting, two polar bodies (probably the second, 

 the first having been absorbed) at/. D. The young Actinosphie- 

 rium escaping from the cyst-wall; the cleavage-nucleus has 

 divided. 



succession to form two 

 polar bodies (nuclei), 

 which degenerate, after 



