Recent Researches on the Saprolegnieae ; a 
Critical Abstract of Rothert’s results. 
BY 
MARCUS M. HARTOG, D.Sc., M.A., F.R.U.I. 
HE study of the spore-formation of the Saprolegnieae as 
-i- a most accessible type has been renewed again and 
again since Strasburger’s ‘Cell-book’ gave an impetus to 
cytology. Biisgen (in Pringsheim’s Jahrbiicher, xiii, 1882), 
and a little later Marshall Ward (in Quart. Journ. Micr. Soc. 
N.S., xxiii, 1883) elucidated the contradictory statements of 
older observers by showing that the zoospores were segregated 
in two distinct stages, interrupted by a third in which the 
contents of the sporange appeared uniform and homogeneous. 
They regarded the clear spaces between the origins (Anlagen) of 
the spores in the first stage as transitory cell-plates (Biisgen), 
or nuclear-plates (Ward), and referred the homogeneous stage 
to the absorption of these plates. They described the appear- 
ance of shifting vacuoles in the young spores on their second 
and definitive separation. Finally, Biisgen expressed the view 
that the substance of the transitory cell-plates of the first 
segregation become converted into the ‘ expulsive substance,’ 
which by its supposed swelling effected the dispersion of the 
zoospores. 
In 1884 a careful examination led me to a totally different 
interpretation of the facts correctly observed by my pre- 
decessors. In a paper first read at the Association Frangaise 
(July 1886), and printed in extenso in the Quarterly Journal 
of Microscopical Science, March 1887, I was able to prove 
that the hypothetical cell-plates of the first segregation are 
merely the optical expressions of thinnings on the parietal 
[Annals of Botany, Vol. II. No. VI. August 1888. ] 
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