86 West and Griffiths . — The Lime-Sulphur Bacteria 
potassium iodide, alcohol, or by drying and subsequently re-irrigating with 
water, the globules pass through the cell-wall and crystallize either on its 
exterior or in the water in the immediate vicinity. The exudation of the 
globules and their subsequent crystallization take about fifteen minutes. 
After prolonged drying this exudation does not occur. The crystals are 
of two forms, flat rhombohedra with angles 74 0 55' and 105° 5', or rhombic 
prisms ( vide Fig. 3). 
The globules are readily soluble in sulphuric acid, hydrochloric acid, 
nitric acid, and dilute acetic acid. They are also dissolved by formalin in 
about an hour. 
The crystals are readily soluble in all the above acids except sulphuric, 
when, after partial solution, dense tufts of small crystals (presumably of 
calcium sulphate) are formed and stop further action. 
If the organisms are heated to redness on platinum foil, the globules 
remain apparently unaffected, and are soluble in the same reagents that 
dissolve the crystals. 
In the Bunsen flame the organisms give the red calcium coloration. 
If sulphuric acid is added to a collection of living organisms, gas is 
given off freely, and when passed into lime-water the gas causes a white 
precipitate. Therefore it consists of, or contains, carbon dioxide. 
If to a collection of living organisms a solution of potassium perman- 
ganate is added, and then sulphuric acid, the permanganate is unaffected by 
the gas given off. There is no carbon monoxide given off, therefore, as in 
the case where calcium oxalate is similarly treated. 
These tests indicate that the globules consist of calcium carbonate. 
This is confirmed by examination of the crystals with the polarizing micro- 
scope. It is found that their optical properties and crystalline form show 
them to be calcite. Such crystals may be produced chemically by adding 
a hot solution of ammonium carbonate to a hot solution of calcium chloride, 
when a mixture of flat rhombohedra and rhombic prisms is produced, 
identical with those formed from the crystallization of the plastic globules 
in the organism. 
While within the organism the globules do not polarize. 
The facts that sulphuric acid will completely remove the globules from 
the living organism, that gas is not given off very freely with dilute acetic 
acid, and that the globules will pass through the cell-wall without rupturing 
it, all appear to indicate that the calcium carbonate is possibly held in 
a colloidal form while within the organism. That there is a difference 
between the properties of the calcium salt in the living organism and in the 
dead organism is also shown by the very brisk effervescence when dilute 
acetic acid is added to specimens that have been subjected to prolonged 
drying, or to specimens incinerated on platinum foil. 
2. Sulphur grains. Small granules varying in diameter from about 2 n 
