PLEOMORPHISM OF THE SCHIZOPHYTA. 501 
already figured by me, as Monas okeni, Monas vinosa, 
and Rhabdomonas warmingii. 
On the other hand, two years later, Dr. Warming, of Copen- 
hagen (‘ Vidensk. Meddelelser. naturhist. For. i. Kjébenhavn,’ 
1875), after studying the same organism and figuring many of 
its form-phases, adopted my view as to their nature, and the ex- 
tension of that view to the Schizophyta generally. He says: 
‘« Les bactéries sont douées en réalite d’une plasticité illimitée, 
et je crois qu'il faudra renoncer au systéme de M. Cohn.” In 
1883 Dr. Neelsen, in his ‘Studien tiber die blaue Milch” 
(Cohn’s ‘ Beitrage,’ vol. ii, p. 241), cites my views and their 
confirmation by. Warming, and rightly contrasts them with the 
later views of Nageli and Billroth, and with that of Lister, who 
conceived that certain Bacteria were developed from a fila- 
mentous fungus (Dematium fuscisporum). As the result 
of his investigation of the Bacterium cyanogenum of blue 
milk, Neelsen says: ‘‘ Viel eher wiirde fiir unsern Fall der 
Ausspruch Lankesters zutreffend erscheinen, von dem Proteus- 
ahnlichen Organismus, dessen einzelne Erscheinungs-formen 
eine Serie von Adaptationen vorstellen.”’ 
In 1884 Prof. de Bary, of Strasburg, in his ‘ Vergleichende 
Morphologie der Pilze,’ p. 511, says, in regard to the question 
of species among the different forms of Bacteria: ‘There 
exist two views on this subject which are, at any rate in appear- 
ance, totally opposed to one another. The first is, as I think 
erroneously, ascribed to Cohn. . . . Cohn distinguishes 
merely what we have above spoken of as form-genera and form- 
species. The other view in its most extreme form amounts to 
this, that all distinction of species among the Bacteria is 
denied, and all forms are regarded as modifications of a single 
species or whatever else it may be called, and these modifica- 
tions can be transformed by cultivation into one another 
reciprocally. This view was (if we leave out of consideration 
older intimations of a similar nature) set up in opposition to 
Cohn’s classification by Lankester in 1873, and by Lister; 
and in 1874 carried to such a length by Billroth, that he 
united all the forms of Schizomycetes known to him under one 
