454 Ferguson . — The Development of the Egg and 
mitotic figure, some of the substance of the spindle-threads 
probably passes into the daughter-nuclei, but the greater part 
of the fibres merge into the cytoplasmic reticulum and be- 
come indistinguishable from it. We have here another evi- 
dence that cytoplasmic and nuclear elements are but different 
expressions of the fundamental or ground substance of the 
cell. When the daughter-nuclei are formed, they present very 
beautiful, moniliform reticula, which later undergo changes 
very similar to those described for the growing egg* nucleus. 
As recorded by Wilson (’96 and ’00), Van Beneden (’83 
and ’ 87 ) made the very interesting discovery, confirmed by 
Herla (’ 93 ), that the chromosomes are formed separately in 
the sexual nuclei of Ascaris megalocephala. The differentia- 
tion of the chromatic segments takes place after the entrance 
of the sperm-nucleus into the egg, but before the two nuclei 
have come into contact. Thus the exact equivalence of the 
chromatic substance in the paternal and maternal nuclei was 
demonstrated. In the following year, Strasburger (’88) sug- 
gested that in the coming together of the nuclear threads lay 
the important point in fertilization. A separating-out of the 
chromatic elements similar to that described by Van Beneden, 
has since been found to occur during fertilization in many 
animals, but has not yet been demonstrated as of frequent 
occurrence in plants. In 1891, Guignard described the forma- 
tion of two distinct chromatic spirems in the conjugation 
nucleus of Lilium Martagon , but he did not figure them, and 
his statement seems to have been overlooked by most later 
writers. Strasburger was able, in 1897, to distinguish the 
maternal and paternal portions of the fertilized nucleus in 
Fucus up to the time when the spindle was fully formed. 
But the results of more recent writers 1 seem to indicate that 
1 Arnoldi (’00) in Cephalotaxus , Caldwell (’99) in Lemna , Campbell (’99) in 
Sparganium , Farmer and Williams (’98) in Fucus , Guignard (’99) in Lilium , 
Harper (’00) in Pyronema , Ikeno (’98) in Cycas , Jager (’99) in Taxus , Land (’00) 
in Erigeron and Silphium , Lotsy (’99) in Gnelum , Merrell (’00) in Silphiu?n> 
Mottier (’98) in Lilium , Mottier (’00) in Dictyota, Nawaschin (’99) in Lilium , 
Nawaschin (’00) in Helianthus , Delphinium , and Rudbechia, Osterhout (’00) in 
Bat rackosper mufti } Shaw (’98) in Onoclea, Thom (’99) in Adiantum and Aspidium , 
