680 TRANSACTIONS OF SECTION K. 
3. Some Effects of Humates on Plant Growth. 
By Professor W. B. Borromury, M.A. 
Peat-moss litter is said to be ‘entirely unsuited for the growth of plants.’ 
It is acid in reaction and contains no soluble humates. 
It has been found, however, that when peat is treated with certain micro- 
organisms a large quantity of soluble humate is obtained and the peat is 
rendered alkaline. An aqueous extract of this treated peat (one part peat to 200 
parts water) will supply all the plant-food necessary for successful water- 
culture experiments. As no trace of nitrate was found in the culture solutions 
during the whole course of the experiments, it is evident that the nitrogen-need 
of the plants was supplied by some form of organic nitrogen present in the 
solution. 
Water-cultures with tomato seedlings, germinated in sterilised sand, showed 
that the plants failed to grow in raw peat-extract, but in treated peat-extract 
the plants grew well, flowered, and produced fruit. Experiments with buck 
wheat, radish, and barley gave similar results. 
4. On some Morphological Varieties of Cladothrix dichotoma (Colin). 
By Professor Davin Ettis. 
Cladothriz dichotoma is one of the thread-bacteria, and is widely distributed 
throughout Europe. Its economic importance is considerable, because its presence 
in iron-waters is associated with the accumulation of the red ferric hydroxide, 
thus causing a considerable impediment to the flow of water through pipes. 
The present investigation has brought to light the following :— 
1. There are morphological as well as physiological varieties of this organism. 
The normal or central variety has sub-polar cilia. The variety under investiga- 
tion possessed polar cilia. Spherotilus natans is probably another variety of 
Cladothrix dichotoma. 
2. Under certain conditions, multiplication is effected by the slipping off, 
sideways, from the parent thread, of small portions, which immediately assume 
a spiral form, develop polar cilia, and, except in the stained condition, are indis- 
tinguishable from members of the Spirillum group. When stained, however, 
these spirilla are seen to be composed of typical rod-cells, enclosed in a common 
sheath. The existence of these ‘ spirilla’ was asserted by Zopf in 1882, but has 
since been denied by subsequent writers. " 
3. The sheath enclosing the rods is composed at first of a thin mucilaginous 
covering, closely investing the rods. The sheath subsequently hardens. By 
appropriate treatment it can be shown that the sheath has transverse septa, 
dividing it into compartments, and that each compartment contains a single 
rod-cell. 
4, Each rod-cell has a well-defined membrane, and in the cytoplasm, besides 
the oil-drops which had previously been found, reserve material in the form of 
glycogen was identified. The cell-membrane seems to serve, in addition to the 
cytoplasm, as a storehouse of food material, as when the organism is cultivated 
artificially, and the threads stained with iodine, the membrane takes up the 
characteristic sherry-brown colour of glycogen. Further, as the reserve material 
became used up, the sherry-brown colour gradually disappeared till the mem- 
brane ultimately appeared quite colourless when treated with iodine. 
5. Multiplication takes place in the case of attached threads by the libera- 
tion of motile or non-motile cells from the opening at the apex, by the slipping 
out sideways of individual cells, or by the growth and multiplication of 
detached fragments. In the case of motile threads, multiplication takes place, 
so far as could be observed, only by the detachment of fragments, which on 
liberation assume motility, and then grow and divide to form mature threads. 
6. The division of the rod-cells takes place in precisely the same manner as 
cells belonging to the bacillus group. 
7. Cladothrix dichotoma shows affinities to the bacillus and_ spirillum 
groups and to the Cyanophycee, but is very far removed from the strepto- 
coceus group with which it has often been confounded. 
wider 
