384 ANNUAL EEPORT SMITHSONIAN INSTITUTION, 1&16. 



a Navicula lyra newly born in the Delaware Kiver is a sister plant 

 of a Navicula lyra born millions of years ago in the island of New 

 Zealand. When, furthermore, it is borne in mind that we are 

 here dealing with a unicellular organism the wonder becomes ac- 

 centuated. Great complexity is also found in the flowers; but a 

 flower consists of millions of cells and the complex of the whole is the 

 sum total of the different parts. But here is one cell, with a single 

 nucleus and microscopic droplet of cytoplasm, which builds for itself 

 its own palace and is to itself its own architect. It is certainly not 

 too much to say that here is a problem in the constructive resource- 

 fulness of animate nature which must long avoo and puzzle the ob- 

 server. 



There is at present a growing interest in the theory that the di- 

 atoms have contributed largely to the world's stock of petroleum. 

 The author does not consider the evidence for this at all conclusive ; 

 as, among other things, there is a significant lack of contiguity be- 

 tween the world's great oil fields and the chief diatom deposits. 

 But the subject is here -mentioned because certain curious facts do 

 lend a strong plausibility, if not a probability, to this theory. That 

 these oils are of organic origin is generally recognized ; and a physi- 

 ological peculiarity of the diatoms, their enormous secretion of oil, 

 ex]3lains why these tiny organisms suggest themselves to an explana- 

 tion of the origin of petroleum. Most plants, during a part of their 

 existence, manufacture more food-material, that is, building mate- 

 rial, than is at the time required for growth ; and this is temporarily 

 stored up as a reserve supply. The chief reserve plant-food material 

 is starch, with sugars, cellulose, inulin, asparagin, etc., as minor sub- 

 stances. But, outside of seeds and nuts, only a few plants store up 

 their reserve supply in the form of oil. The diatom is perhaps the 

 most remarkable in this respect. Living diatom plants will alwaj'S 

 be found to contain from two to ten shining oil globules, deep 

 orange-yellow in color, and Avith a high refractive index. The bulk 

 of this oil, in proportion to the size of the diatom, rarely falls below 

 5 per cent; and the author has samples of diatom material in which 

 a careful measurement of the contained oil shows a proportion of 50 

 per cent. If we consider, therefore, the large extent of many of the 

 known diatom deposits and their frequency in most parts of the 

 world, it becomes evident that the potential volume of organic oil 

 from this one source is very large. But, as above intimated, the 

 application of cause and effect to the diatom-petroleum theory is at 

 present very far from satisfactory. 



In the diversified uses of the diatoms, if there be one that is of 

 supreme importance, it is the value of these organisms as the great 

 fundamental food supply of the marine world. In the sea as on the 

 land, animal life is dependent upon plant life for the transformation 



