On the Retention of Vitality by Alga, 93 
of thanking Dr. E. J. Russell for so kindly providing me with this 
valuable material. 
The cultures were set up in small glass boxes or in small 
conical flasks closed with a plug of cotton-wool, great care being 
taken to ensure that perfectly sterile conditious were obtained. 
The sterile culture solution was introduced into the vessel to a depth 
of about half an inch, and 3 or 4 grams of the soil were then added 
by means of a sterilised spathula, 3 cultures of each soil being made. 
The closed vessels were placed under glass bell-jars in a north 
window and allowed to remain untouched until signs of growth 
appeared in the cultures. 
The culture-medium used was an aqueous mineral-salt solution 
having the following composition :— 
Potassium dihydrogen phosphate (KH 3 P0 4 ) 
l’O gm. 
Sodium nitrate (NaNO s ) . 
10 gm. 
Magnesium sulphate (MgSOJ 
•3 gm. 
Calcium chloride (CaCl 2 ) ... . 
era 
3 
Sodium chloride (NaCl) 
•1 gm. 
Ferric chloride (PeCl 3 ) 
•01 gm. 
Distilled water. ... . 
1000 cc. 
Very slow evaporation took place from the surface of the liquid, 
and this was remedied by very occasional watering with sterilised 
culture solution of about a quarter to one-half of the original 
strength. 
The first growth observed in the cultures was the appearance 
of a white scum over the surface of the liquid ; this was found to 
consist of bacteria. Later, the scum began to assume a green 
tinge of colour and was found to contain numbers of small 
unicellular green algae. 
The growth of moss protonema from some of these soils has 
already been recorded 1 but at the time of writing the algae had not 
developed sufficiently for their identity to be determined ; the first 
trace of moss protonema was observed in the Barnfield soil on Dec. 
30th, 1915, whereas algae were not detected in the cultures until 
about four months later. Green algae grew first and were found in 
all of the cultures early in May, 1916; they produced chiefly a green 
stratum on the surface of the liquid and on the sides of the vessel, 
but the whole liquid assumed a light green colour owing to the 
1 Bristol, B. M. “ On the Remarkable Retention of Vitality of Moss 
Protonema .” New Phytologist, Vol. XV, No.7, July 1916. 
