110 Proceedings of the Eoyal Society of Edinburgh. [Sess. 
X. — Fossil Micro-organisms from the Jurassic and Oretaceous 
Rocks of Great Britain. By David Ellis, Ph.D., D.Sc., Royal 
Technical College, Glasgow. (With Two Plates.) 
(Read November 16, 1914. MS. received November 19, 1914.) 
Introduction. 
Through the kindness of Mr Wallace Thorney croft of Plean, a number of 
slides came into my possession which had been prepared from various rocks 
belonging to the Jurassic and Cretaceous periods. The rocks from which 
these slides were prepared were part of a collection which had been gathered 
together in connection with borings for ironstone, and were in consequence 
highly ferruginous in composition. I undertook the examination of these 
slides in the hope of seeing traces of iron-bacteria, the skeletons of which, 
superimposed by ferric hydroxide, form to-day the bulk of the red fer- 
ruginous deposit in the beds of the “ iron waters ” or ‘‘ ochre waters ” in 
different parts of the world. Apart from the possible value of such organ- 
isms as rock-builders, it was deemed necessary to ascertain whether similar 
micro-organisms played the same role in Jurassic times that the iron 
bacteria do to-day ; for there cannot be any reasonable doubt that there 
must have been “ iron waters ” then as now, and that brownish-red streams 
of iron water could be seen issuing from clefts in the hillsides, or bubbling 
up from the older rocks. 
At the present day practically the whole of this red ferric hydroxide is 
deposited on the membranes of dead iron-bacteria. If, then, similar micro- 
organisms became, during Jurassic times, coated with ferric hydroxide, the 
chances of their preservation would become greatly enhanced. It was 
further considered that if particles of dead organic matter could be pre- 
served in a fossil condition, there was no reason why, if this matter were 
in a putrefactive condition before engulfment, the micro-organisms causing 
this putrefaction should not also be preserved. This would be the more 
probable when, as in the case of the modern iron-bacteria, the membranes 
of the putrefactive organisms become coated and probably replaced by a 
thick resistant crust of ferric hydroxide. 
Then with regard to identification of such micro-organisms, it must be 
borne in mind that rock sections can be cut so thin that they permit . of 
examination under a yV imniersion lens, so that the magnification under 
which the objects are examined is so great that a trained mycologist is not 
