QUARTERLY CHRONICLE OF MICROSCOPICAL SCIENCE. 401] 
especial reference to the possible occurrence of conjugation 
amongst them. ‘They failed entirely to detect anything of 
the kind, the zoospores coming to rest and germinating 
within twenty-four hours. They conclude, therefore, that 
the problem of the sexuality of Pheosporee will be solved, 
not by the further study of the zoospores of these alge, but 
by the detection of female organs which have hitherto eluded 
observation. 
I must conclude with an historical reclamation. I am 
indebted to Dr. Carpenter for pointing out to me that in 
1848 Thwaites! indicated that sexuality existed in its most 
generalised form in conjugation, a view of which [ attri- 
buted the first conception to De Bary (supra, p. 299) ten 
years later. 
I may also add that, as early as 1854? Cohn pointed out 
the morphological parallelism which exists amongst Thallo- 
phytes in which chlorophyll is present and those in which 
it is absent. 
W. T. Tutsetton Dyer. 
1 «Ann. Nat. Hist.,’ 2nd series, vol. i, p. 163. 
? “Nov. Act. Acad, Nat. Cur.,’ vol, xxiv, p, 141. 
