ALTERNATION OF GENERATIONS 27 
nuclear membrane, the chromatin in each falls together in little 
masses, the nucleolus lying by the side of the mass; these then 
separate, a spindle is formed with an equatorial plate and the 
chromatin masses pass at different rates towards the poles. 
The nucleoli then disappear, and four chromatin balls are 
formed which are the daughter nuclei. Only after this is com- 
pleted, do they separate into two pairs, and the formation of a 
cell-wall begins (Dittschlag). 
THE ALTERNATION OF GENERATIONS. 
Assuming, as we are now justitied in doing, the truth of the 
foregoing ideas, we may represent the alternation of genera- 
tions in a typical Uredine by the following diagram : 
basidiospores 
teleutospore basidium 
SPOROPHYTE | GAMETOPHYTE 
(2n generation)| (n generation) 
. spermatium 
uredospore ¢ gamete 
ecidiosporé ? gametes 
intercalary cell ea at 
The n generation is that in which the nucleus has the 
haploid number of chromosomes or, if there are no distinct 
chromosomes visible, the single amount of chromatin ; in the 
2n generation each cell has the double (diploid) number of 
chromosomes or the double amount of chromatin, at first sur- 
rounded by two nuclear membranes, afterwards by one. 
