188 DR. D. H. SCOTT ON NUCLEI 
On Nuclei in Oscillarfa and Tolypothrix. 
By DuxrnFiecp H. Scofr, M.A., Ph.D., F.L.S. 
[Read 16th June, 1887.] 
(Prate V. figs. 1-4.) 
In all recent classifications of the Vegetable Kingdom the class 
of Schizophyta, including, on the one hand, the “blue-green 
Algæ,” and, on the other, the Bacteria, has been sharply sepa- 
rated from all other plants. The chief grounds on which this 
separation is based are three in number :—1st. The absence in 
the Schizophyta of any sexual reproduction; 2nd. The absence 
of distinctly differentiated chromatophores; and 3rd. The absence 
ofnuclei. It is with the last point alone that we are now con- 
cerned. Statements alleging the existence of a nucleus in these 
plants have indeed been made from time to time. Thus Schmitz 
once believed that he had found a nucleus in Oscillaria itself and 
other Cyanophycex ; but he afterwards found reason to give up 
this view. Zopf made similar assertions with regard to Phragmo- 
nema and an allied genus. Here, however, it remained uncertain 
whether the bodies detected by him were really nuclei or simply 
vacuoles. 
Since the exhibition of the under-mentioned specimens, the 
writer's attention has been called to a paper by N. Wille *, in which 
the existence of a nucleus in Tolypothrix lanata is maintained on 
the ground of very careful observations in which various staining- 
reagents were used. So far as itis possible to judge from a paper 
in which there are no figures in illustration of this point, it appears 
that Wille had really solved the problem. Indications of divi- 
sion-stages also seem to have been seen by him. There is, how- 
ever, an absence of satisfactory detail from the paper. Wille's 
work appears to have attracted little or no attention, in spite of 
its considerable merit. Two years later Hansgirg t, in the same 
publication, asserted that both nuclei and chromatophores are 
present in Gleotheca and other forms, though he did not find 
them in Oscillaria or its near allies. His figures, however, throw 
no light whatever on the subject. Within the last few weeks 
& series of papers by Zacharias, which is not yet complete, has 
appeared in the * Botanische Zeitung. His subject is the nucleus 
* Berichte d. deutschen botanischen Gesellschaft, 1883, p. 243. 
t Berichte, 1885, p. 18. 
