202 Hartog . — Recent Researches 
layer of protoplasm left by the aggregation into the c origins 5 
of zoospores, or of lacunar spaces between the latter filled 
with cell-sap. I interpreted the homogeneous stage as con- 
sisting ‘essentially in the swelling up of the protoplasm and the 
loss of its resistance to osmosis/ accompanied but not caused 
by plasmolysis; and regarded it as ‘ probable that the “ Haut- 
schicht ” and vacuolar walls break up at this stage as con- 
tinuous layers/ and that therein was the explanation of the 
phenomenon. I also pointed out that a contraction of the 
sporange can be observed at the homogeneous stage, ac- 
companied by the excretion of a dissolved substance strongly 
attractive to certain bacteria. 
A second part of my paper dealt with the liberation of 
the zoospores. I disproved by the use of reagents the existence 
of any swelling expulsive matter in the sporange, proved the 
correctness of Cornu’s discovery of flagella in the sporangial 
zoospores of Achlya , and referred the liberation to the auto- 
motility of the zoospores reacting to the chemical stimulus 
of dissolved oxygen in aerated water. 
Two other accounts have now appeared ; one by Berthold 
incidental to his work on ‘ Protoplasma Mechanik/ 1886 ; and 
a paper by Ladislaus Rothert which appeared in Polish in 
the Proceedings of the Cracow Academy, xvii, 1887 (it was 
only ‘ in the press ’ in September of that year), and in German 
in Cohn’s Beitrage for 1888. As Rothert’s work is fuller than 
Berthold’s, and in no way contradicts it, I shall only deal with 
the former author. It is interesting to note that all of us 
except Berthold began, at least, our work in the Strassburg 
Institut, under the stimulus and aid of the same kindly 
master — Anton De Bary. 
Rothert’s paper we may greet as affording the first full and 
complete account of the double segregation and homogeneous 
stage, worked out independently, but confirming my views so 
far as they went, and completing them by showing what is 
the real cause of the solution of continuity in £ Hautschicht’ 
and vacuolar wall. His paper however does more than this ; 
it affords the first complete account we have of the formation 
