92 
B. Muriel Bristol. 
ON THE RETENTION OP VITALITY BY ALG^ 
FROM OLD STORED SOILS. 
By B. Muriel Bristol, M. Sc. 
[With Two Figures in the Text], 
I. Method of Culture and General Observations. 
D URING the course of a series of experiments on Soil-Algae 
which have been under investigation for the last three years, 
a number of cultures were made, in October 1915, of some old 
stored soils from the Rothamsted Experimental Station, Harpenden, 
and as a result of these cultures some very interesting facts have 
been observed in regard to the length of time during which algae 
are able to retain their vitality under adverse conditions. 
The samples of soil used were collected from the various 
experimental plots at Rothamsted, and after being partially air 
dried were passed through a sieve having ^-inch meshes. They 
were then placed in large bottles and sealed with leaden capsules, 
so that neither foreign infection from outside nor evaporation of the 
contained water could take place. The first soils examined had 
been taken from Broadbalk in 1893, 1881, 1869, 1868, 1865, 1856 and 
1846 respectively, from Agdell in 1867, from Barnfield in 1870, from 
Hoosfieldin 1868 and from Geescroft in 1865. They remained in 
the original bottles until 1912 when representative samples were 
taken by Dr. T. Goodey, to whom I am greatly indebted for the 
material, and placed in small sterilised bottles closed with a plug 
of cotton-wool. The water-content of the soils at this time varied 
rather considerably, some containing only about 3-5%, while others 
contained as much as 10% of water; but in no case was there 
sufficient water present for active vegetative growth to have been 
taking place. From 1912 onwards a gradual desiccation of the soils 
took place through the cotton-wool stoppers until, in October 1915^ 
they contained only about 3% of water. The samples from 
Broadbalk 1865 and 1856 and from Geescroft 1865 differed from the 
others in that they had been moistened in November 1913 to bring 
the water-content up to 18%; they had then undergone gradual 
desiccation as the others had done. 
In April, 1916, cultures were made of additional samples of the 
Barnfield 1870 soil obtained from the original bottles at Rothamsted 
which had remained sealed since 1912; and I take this opportunity 
