Dec. 21, 1888.] 



SCIENTIFIC NEWS. 



635 



nevertheless the process was continually going on, and 

 silica, by that series of actions which had been demon- 

 strated by actual experiments, was passing continually 

 into a state of solution. That slow and gradual action, 

 in contradiction to the sudden and brutal mode of 

 treating things which was characteristic of our chemical 

 laboratories, was very characteristic of the operation of 

 nature. The result of that action was that all natural 

 waters contained silica in solution. As they had seen, the 

 waters of those hot springs, the geysers, contained an enor- 

 mous proportion of silica in solution — which was rapidly 

 deposited, but all these natural waters of the globe, 

 and the waters of rivers and lakes, as well as of 

 springs, the waters of the ocean — all these natural waters 

 contained silica in solution, but in very minute propor- 

 tions. Indeed, the proportions were so minute that it 

 almost defied the art of the most careful chemist to de- 

 termine what the proportion was. For example, he 

 had a number of analyses of different rocks, and the 

 quantity of silica in many of them was very minute ; but 

 if they had an analysis of natural waters the quantity of 

 silica present in each of them would have to be repre- 

 sented by he did not know how many noughts following 

 the decimal point, and then followed by some small 

 figure. The experiments on the waters of the ocean had 

 shown that the quantity of silica in the ocean was always 

 less than one in 50,000, and in most cases less than one 

 in 100,000, and in some cases much less than that ; so 

 they saw the natural waters, whether they were the 

 waters of springs, or of rivers, or of lakes, or of the ocean, 

 contained silica in solution ; yet they contained almost 

 inconceivably small proportions of silica ; and the ques- 

 tion might arise, how could that almost inconceivably 

 small proportion ever become separated from the enor- 

 mous quantity of water in which it was dissolved ? Of 

 course they might take large quantities of this water and 

 boil it down, thereby turning the water into steam, in 

 which case all the dissolved matters, including the silica, 

 would be left at the bottom. But that was not an opera- 

 tion that went on commonly in nature. The ocean was 

 not boiled down periodically, or even the lakes, in order 

 to get out the silica ; but there was an agency at work, a 

 very important agency indeed, by which this silica was 

 concentrated and separated from the water of the ocean, 

 from the waters of lakes, from the waters of rivers, of 

 springs even, and the water flowing over the surface of 

 the earth,when it fell as rain,silica was taken up in all these 

 cases, and it was concentrated from this water, separated 

 from this water by the wonderful agency to which he 

 had already called their attention. As he had already 

 pointed out to them, there were remarkable organisms 

 which took water into their organisation with their 

 food, and in the process of breathing which went 

 on in marine animals. Those waters were taken into 

 their organisation, and the silica was separated from the 

 water, minute as it was in proportion ; it was separted in 

 the solid form, and formed the skeleton, or the hard part, 

 of these organisms. They would recollect that he pointed 

 out to them that there were three classes of organisms 

 which had that wonderful power of separating silica from 

 its state of solution. The first of these organisms were 

 the excessively minute ones, the plants known as the 

 diatomacae, or, for short, diatoms ; and he would bring 

 before them those diatoms as showing them the wonder- 

 ful forms assumed by their skeletons. They were ex- 

 quisite little objects, each consisting of two valves, like 

 portions of pill-boxes, one fitting inside the other, but so 



excessively minute that many of them could be onlyjust 

 seen even by the highest powers of the microscope, and 

 in many d.i.ses they were covered with the most ex- 

 quisitely beautiful ornamentation, as shown in some 

 figures he exhibited, which were only a few selected out 

 of many, many thousands of known forms. These 

 skeletons were composed entirely of colloidal silica which 

 had been separated from its state of solution in water. 

 Then there was a class of minute animals that lived both 

 in marine and fresh water, and in water which was a 

 mixture of both, and some of them inhabited fresh water, 

 and all the forms that lived under these different condi- 

 tions were very distinct. The radiolarians only lived 

 in the sea. They were strictly marine forms. These 

 radiolarians were so minute that many of them hardly 

 reached the size of a pin's head, but they were gigantic 

 compared with diatoms. The radiolarians assumed an 

 enormous variety of forms. (A small selection of forms 

 were exhibited.) 4,000 forms were described as being 

 found by the Challenger Expedition, and Dr. Haeckel 

 admitted that he was far from having described the 

 whole of them. There was still a third class of organisa- 

 tions, the silicospongia, siliceous sponges, which had 

 skeletons which were as much larger than the radio- 

 larians as the radiolarians were larger than the diatoms, 

 and some of the forms of the rods building up 

 the skeletons of the siliceous sponges were shown. 

 Now, these organisms were all very minute — the diatoms 

 excessively minute — but, nevertheless, they made up in 

 numbers what they wanted in size ; and as they had 

 already seen, there was at the bottom of the ocean exten- 

 sive deposits of white, sticky mud, some of which were 

 entirely made up of diatoms, and these were called the 

 diatomaceous oozes, and others were made up of radio- 

 larians, and these white muds were ca ( lled the radio- 

 larious oozes ; and although they did not find mud made 

 up entirely of sponge-spicules, there were many that 

 were largely made up of them. But besides that, they 

 found among the rocks of the globe many deposits, made 

 up of these organisations, consisted chemically of silica 

 and nothing but silica, which formed those materials 

 known as tripoli and diatomite. These were made up of 

 the skeletons of these diatoms. If they took the minutest 

 fragment, they got hundreds and thousands of these 

 marine creatures sprouting together. They could be 

 examined under a microscope, and a wonderful variety 

 of forms could be seen ; hundreds and thousands of 

 forms might be detected in one of these deposits. So 

 again, in other parts of the earth they found rocks made 

 up of radiolarians. In the Island of Barbadoes there 

 was a rock covering many miles of country, and of con- 

 siderable thickness, entirely made up of these radio- 

 larians ; and in other places, again, they might find beds 

 of siliceous rock, as Dr. Hinde so well showed, which, 

 when examined by a microscope, were seen to be made 

 up of sponge-spicules. The part played by those 

 organisms seemed to be in inverse ratio to their size. 

 The deposits were greater as the things were smaller. 

 They did not find great rock-masses made up of bones-of 

 elephants, but they did find them made up of micro- 

 scopical foraminifera: The most important deposits were 

 made up of the smallest organisms, the diatoms ; the next 

 important were made up of the radiolarians; and com- 

 paratively thin and unimportant deposits, though not 

 insignificant, were made up of siliceous sponges. This 

 was Nature's way of effecting most astounding results by 

 means of the smallest and most insignificant agencies. 



