English Soils: an Important Factor in Soil Biology. 75 
8. Dactylococcus dispar , W. and G. S. West. 
This curious form was observed in the cultures of one soil. The cells 
varied considerably in shape, being either lunate or somewhat distended and 
irregular. The two extremities of the cells were unequally developed, one 
often being rounded and the other acute or acuminate and sometimes bent, 
but there were no prolonged apices as in the last species. The cells were 
13 to 19 \x long and 2*5 to 6 /x broad, with a parietal chloroplast but no 
pyrenoid. Multiplication took place by the formation of four autospores. 
9. Chlorococcum humic ola, (Naeg.) Rabenh. 
This species was found in the cultures of every soil but one. The cells 
contained a single parietal chloroplast with a variable number of pyrenoids, 
and were observed to multiply either by the formation of zoogonidia or by 
means of aplanospores which gave rise to a palmella-state. A full account 
of the life-history and cytology of this alga has been given in a separate 
paper, 1 however, and further details are unnecessary here. 
10. Chlorochytrium par adoxum, (Klebs) G. S. West. 
This alga has also been fully described elsewhere. 2 It occurred in 
three different soils and agreed in every detail of its life-history with the 
description given by Klebs. The chloroplast consisted of a small spherical 
axial portion from which radiated outwards in every direction variously 
lobed and branched arms, the ends of which flattened themselves against the 
cell-wall. 
11. Vaucheria Jiamata , (Vauch.) Lyngb. 
The filaments of this species, which was identifiable in only one soil, 
were 35 to 39 fx broad. The oogonia were produced singly on the end of 
lateral branches about 65 [x long, and were subspherical, about 56 /x long by 
62 fx broad, with very thick walls. Each antheridium grew on the end of 
a filament branching out from the lower part of the oogonial filament and 
was about 18// in diameter and strongly curved. 
The dimensions of this form are somewhat small for the species in 
every respect, but the mode of growth and general characters leave no doubt 
as to its identity. 
1 2. Vaucheria sp. ? 
In four other soils vegetative filaments of Vaucheria were observed, 
but in none of them were reproductive organs to be found, and consequently 
identification was impossible. In two cases the filaments almost exactly 
resembled those of the last species, but in the others they were usually wider, 
up to 60 }x in diameter. 
1 Bristol, B. M. : On the Life-history and Cytology of Chlorococcum humicola, (Naeg.) Rabenh. 
Journ. Linn. Soc., Bot., vol. xliv, July, 1919. 
2 Bristol, B. M. : A Synopsis of the Genus Chlorochytrium, Cohn, Journ. Linn. Soc., Bot. 
(inedit). 
