No. 463.] STUDIES ON PLANT CELL.— VI. 481 
of the chromosomes in the mitoses of sporogenesis were longi- 
tudinal with somewhat varying views, however, as to the exact 
time when the two divisions take place. On the other hand 
Ishikawa ('97), Calkins (°97), Belajeff ('98), and Atkinson (99, 
for Trillium) have claimed that the second mitosis presented a 
transverse division. Dixon ('95, '96, : 00) and Schaffner (97) 
held a position apart from all these investigators, believing, that 
the chromosomes of the first mitosis of Lilium resulted from 
loops whose free ends became appressed or twisted together 
finally separating at the angle of the loop and thus constituting 
a transverse division in this first mitosis. These latter observa- 
tions accord with the latest conclusions of Farmer and Moore 
(:03) and Strasburger (: 04b). Most of this literature is reviewed 
in detail in Strasburger's paper of 19008. We shall omit an 
historical discussion of this early work for the entire subject is 
approached from quite a different standpoint in the series of 
papers which have appeared in the past three years (1903-05) 
and which give hope of much clearer information on the mitoses 
of the spore mother-cell. 
The remainder of this treatment of “ Reduction of the Chro- 
mosomes” will take up the recent papers and try to show the 
drift of the present investigations. These papers had not 
appeared when the author described the behavior of chromo- 
somes during mitosis in Section II (Amer. Nat., vol. 38, p. 445, 
June, 1904) and presented the account of the spore mother-cell 
in Section III (Amer. Nat., vol. 38, pp. 726, 740, Oct., 1904). 
At that time it seemed probable that Strasburger's conclusions 
of 1900 held true for all plants, namely, that the chromosomes 
split longitudinally in both mitoses of sporogenesis as well as in 
all other mitoses of the life history. Whether these views may 
have to be materially changed in the light of the most recent 
work is now a matter of dispute. Yet the ground has shifted 
so frequently in these perplexing problems that it is hard to feel 
sanguine of final conclusions even in the hopeful situation of the 
present. I shall take up the events of sprogenes in order, 
beginning with the growth period and synapsis and ending with 
the two mitoses of the spore mother-cell. 
The growth period always extends over a considerable length 
