230 NATURAL SCIENCE [October 
in a subsequent note to this paper the authors state that they have 
found a great number of Archacocyathinae at Normanville in lime- 
stone, which “ appears to be conformable to strata which most resemble 
those in which the radiolarian casts have been observed.” Hence 
they are inclined to believe that the Radiolaria may be in Lower 
Cambrian or passage beds rather than Pre-Cambrian. 
FREEZING OF PLANTS 
Messrs GusTAV FiscuEr, of Jena, have just issued, in book form 
(73 pages 8vo), an account of some researches by Prof. Hans 
Molisch on the freezing of plants. The author, by means of an 
arrangement which he describes in the first chapter, has observed 
under the microscope the changes which occur in freezing not only 
in plant-cells and tissues, but also in colloidal substances, emulsions, 
coloured liquids, and salt-solutions. For observation the microscope 
is placed in a triple box. The outer case is of wood, then comes a 
hollow-walled zinc chamber, inside which is fitted the instrument, 
the tube projecting through the top. Sawdust is placed between 
the outer wall and the zinc chamber, and the hollow walls of the 
latter contain the freezing mixture. A wide zinc tube allows 
light to pass from the outside to the reflector. Several figures are 
given, showing the appearance of non-living substances as freezing. 
In all cases particles of ice are formed by separation of the water, 
while the gum, particles of latex or concentrated salt-solution 
occupy the intervening spaces. Three figures (p. 17) of an amoeba, 
alive, frozen, and thawed respectively, are of interest. In the 
frozen state the organism forms a lump of ice intersected with a 
highly complicated network, consisting of protoplasm very poor in 
water, concentrated cell-sap and air-bubbles. When thawed there 
is a much less sharply defined reticulum of dead protoplasm, the 
lacunae in which are the spaces which in the frozen state were filled 
with ice. Spirogyra cells (p. 22, fig. 10) in freezing lose about half 
their diameter by withdrawal of water, which then freezes on the 
outside ; on thawing the cells swell to their original size, but proto- 
plasm, chlorophyll band and nucleus form a disorganised central 
axis between which and the walls is contained the water. 
After experimenting for five winters with hundreds of objects, the 
author comes to the conclusion that, asa rule, it is immaterial to the 
preservation of the life of the object whether thawing is rapid or 
slow, and that death by freezing is the result of an excessive loss of 
water, through ice formation, if the protoplasm by which its struc- 
ture (“architektur ”) is destroyed, and that all the facts of the case 
can be easily and naturally explained from this point of view. 
