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The Cytology of Cotton. 
Explanation of Plate V., 
Illustrating Mr. E. S. Salmon’s Paper on “Certain Biologic Forms 
of Erysiphe in Cases of Non-Infection.” 
Figs. 1, 2, 3, 4, 7. Conidia of the “ biologic form ” of Erysiphe 
Graminis on wheat germinating on the epidermis of barley 
leaves; i.h., incipient haustoria; d.h., haustoria in process of 
disorganization. In Fig. 1 the germ-tube has entered a stoma ; 
in Fig. 2 the germ-tube has passed over the open stoma, 
formed an appressorium, and developed a haustorium in the 
subsidiary cell. 
Figs. 5, 6. Final stage of development reached by two conidia of 
the “ biologic form ” of E. Graminis on Bromus racemosus 
germinating on the epidermis of a leaf of B. commutatus. 
(All the Figures x 400.) 
THE CYTOLOGY OF COTTON. 
Preliminary Note. 
A N examination of the cotton flower at various stages of its 
fy development has provided the following information :— 
The development of the sex-cells from a sub-epidermal arche- 
sporium is normal, reduction of the mother-cell taking place in the 
usual way, although very rapidly, and producing gametes with ten 
chromosomes, the zygote nuclei apparently containing twenty. 
The tetrad cell nearest the micropyle becomes the megaspore. 
Fertilisation occurs within twenty-four hours of pollination, the two 
polar nuclei fusing just before the union of the second male 
nucleus with one of them. The tube nucleus also passes into the 
embryo sac, but degenerates. After three days the egg cell divides 
into two, the endosperm nucleus having now produced over one 
hundred daughter nuclei, whose divisions are very irregular. No 
suspensor is differentiated by the embryo. 
The initial stages of development of the cotton fibre are quite 
at variance with the accepted accounts, the cotton itself being a 
simple epidermal hair. 
The nucleoli, which are seen in many cases to be continuous 
with the reticulum, retain their individuality in the first few divi¬ 
sions both of the egg and of the triple nucleus. The linin thread 
also appears to persist in the reduction of the male mother-cell, 
until after the chromosomes have attained their usual contracted 
form, and the multipolar spindle is appearing, but owing to their 
small size detailed investigation of the reducing cells is difficult. 
The full account will be published later. 
W. L. Balls. 
Cairo, Oct., 1905. 
R. MADLEY, PRINTER, WHITFIELD STREET, W. 
