2/8 



REDUCTION OF THE CHROMOSOMES 



earlier divisions the number is approximately double this (8-9). This 

 observation makes it nearly certain 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 



A 



C 



A B C 



Fig. 138. — Conjugation and formation of the polar bodies in Adbiophrys. [SCHAUDINN.] 

 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 Wolters ('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- 

 P' fi':''r~"'\^h:^ mined. Schaudinn 



('96, 2) has observed a 

 like process in Acti- 

 noplirys, each of the 

 gametes segmenting 

 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- 

 ^ D haps to its rapid dis- 



Fig. 139. — Formation of polar bodies and conjugation in mtCgratlOn. \w ActlTlO- 



AciinospkcBrium. [R. HERTWIG.] sp/i(£)'i?tm, according to 



A. Two gametes ("secondary cysts"), resulting from the ji Hertwio" ('q8) the 



division of a "primary cyst"; second maturation-spindle in • t> ^ =' '' 



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



polar bodies (/>!,/ 2) formed in the right gamete, the second ^iyjfjgg twice in rapid 



one forming in the left gamete. C. Subsequent fusion of the _ ^ 



gametes; nuclei uniting, two polar bodies (probably the second, SUCCCSSIOU tO tomi tWO 



the first having been absorbed) at/. D. The youns, Acfi/iosphie- pQl^j- bodicS (nUclci), 



1Z:t^^ '"" "" '"'"'"' *' '^'^^^^-^""^'^''"^ '^^ which degenerate, after 



