1905.] 



On the Synapsis in Amphibia. 



561 



a b c 



Diagram representing the course of the synaptic metamorphosis. For the sake of 

 clearness only six chromosomes are represented in the premaiotic resting cell (a). 

 At (b) the chromosomes are uniting ; (c) shows the conversion of the gemini into the 

 young loops. At (d) is seen the split in the chromosomes ; (e) shows a later stage ; 

 (f) shows the transformation of the loops into the adult gemini (heterotype chromo- 

 somes) ; (g) represents their appearance on the spindle ; (/() shows the diastral 

 chromosomes, three in each cell, with the longitudinal split begun in the preceding 

 prophase. 



optical power and efficient preservation are combined, that : The somatic 

 chromosomes are visible in the resting cells ; that during the inception of the 

 synaptic phase these chromosomes pair so as to form double bodies which are 

 the forerunners of the adult gemini (heterotype chromosomes, allotype 

 chromosomes, bivalent chromosomes, etc.) ; that by growth and elongation 

 the gemini constitute the polarised loops of the first maiotic prophase ; that 

 these loops become longitudinally split, and later each longitudinally fissed 

 aggregate rolls itself up into one or other of the forms assumed by the adult 

 gemini ; that in these later stages in Triton the longitudinal fission of the 

 chromosomes becomes almost, but not quite closed up, and in the diaster 

 the separated chromosomes again exhibit it : while finally it is seen that this 

 split functions in the second maiotic (homctype) division. 



