STUDIES OF REPRODUCTIVE ELEMENTS: I. 3 



ronld not be exactly made out, except in tlie srages just before 

 and during the division. At this stage each chromatic; element 

 assumes at first a rod-like shape, and then becomes constricted in its 

 median portion, transversely to its long axis, thus resemblino- in 

 shape a dumb-bell (fig. 2, left end). These dumb-bell shaped bodies 

 are eight in number, and arrange themselves in form of a rino- on 

 whose periphery they lie. This is the stage of the spindle. Tt will 

 be noted that the s})indle appears different to the eye according to 

 the methods «jf preservation we use. Thus preparations treated with 

 hot-alcoholic sul^limate (30 % alcohol to which a few drops of con- 

 centrated sublimate solution have l^eeii added) show no achromatic 

 fibres connected witli the chromatic elements, while those cells which 

 are killed with aceto-picric-acid exhibit them verv distinctly. The 

 central Ijodies can also be clearly made out witli Grenadier's haema- 

 toxylin. Jn the process of division each dumb-bell shaped chromo- 

 some elongates and becomes divided in its middle part, so that one 

 luilf of the d(unb-bell goes to one pole and tlie other half to the other. 

 The two (laugliter cells arising ])y division of a mother cell contain 

 each eight single chrom(js()mes, each of which is half one of the 

 original cliromosomes. The only différence from tlieordinarv karyo- 

 kinesis consists in the mode of division of the chromosomes, which 

 generally divide longitudinally and not transversely. 



Fig. 2 represents more highly magnified the extreme posterior 

 end of the testis shown in fig. 1. AVe now see a number of primi- 

 tive sperm-cells with very large nuclei, the chromatic elements of 

 which appear as so many minute rods. At the left hand corner is 

 seen one of the cells in division, in wliich five dumb-bell-shaped chromo- 

 somes are represented in a single row at the equator of the spindle ; 

 the other three, not here visible because lying at a lower level, could 

 be made out by focussing the microscope. At the i-ight hand 1 ha\e 



