290 PROCEEDINGS OF THE AMERICAN ACADEMY. 



by improved technique on the microtome, are spores of vascular 

 cryptogams. 



3. The proof that the constituent micro-organisms of boghead 

 coals are not Algae but spores, overthrows the algal hypothesis of the 

 origin of petroleum and similar substances. 



4. It appears clear that petroleum products have been derived, 

 mainly at any rate, from the waxy and resinous spores of vascular 

 cryptogams laid down on the bottoms of the shallow lakes of the 

 Coal Period. These lacustrine layers, either as cannels, bogheads 

 or bituminous shales, according to the sporal composition and the 

 admixture of earthy matter, are the mother substance of petroleum. 

 Pressure and temperature either separately or combined, in the 

 presence of permeable strata, have brought about the distillation 

 of petroleum from such deposits. 



