496 TRANSACTIONS OF THE CANADIAN INSTITUTE. (Vor. VIII. 
logists. They are clearly connected for the most part, with the basic 
eruptives of Archean date.” 
3. In 1876 Sir William Dawson presented a paper to the Geological 
Society of London* in which a new and novel theory was developed. 
The Laurentian gneisses were altered sediments; the deposits of apatite 
occurring in proximity to them were also to be considered as metamor- 
phosed clastic rocks, and not only so but they are derived from depositions 
of organic remains. Around the hypothesis thus propounded has raged 
one of the most vigorous discussions in the later history of the science. 
Once it is proved that we have undoubted remains of organic life in strata 
thus low in the geological series an important biological fact has been 
attained. 
4. Still another theory was brought forward by Professor Boyd 
Dawkins, in 1884.° He concluded that the deposits are in the 
form of true veins and that the phosphoric acid is brought from the deeper 
seated rocks by means of hydrothermal action. But, according to Bell® 
the almost universal presence of phosphoric acid in igneous rocks, 
coupled with its marked power of segregation, suggests a much more 
obvious source. In the discussion arising from Dawkins’ paper, a modifica- 
tion of his vein theory was suggested by Kinahin. In this he en- 
deavoured to account for the occurrence of apatite in a corresponding 
manner to that of phosphorites by supposing the action of phosphoric 
acid on a calcite vein stone. 
5. These three theories so radically different and so irreconcilable 
can each lay claim to many supporting facts and it becomes of importance 
to classify and compare these. It is evident that they may be grouped 
into five separate divisions as follows: 
I. The evidence supplied by the associated rocks, their chemical 
composition and geological form. 
II. The evidence supplied by the geological form, veined, bedded 
or eruptive of the deposits themselves. 
III. The evidence supplied by the chemical and physical peculiarities 
of the apatites. 
4 Dawson—Quart. Jour. Geol. Soc. 
5 Boyd Dawkins—Manch. Geol. Soc. 
6 Bell—Eng. Mining Journ. 
