1909] on Advances in Knoivledge of Silicon. 649 



All theories of life assume that its phenomena are inseparably 

 associated with certain complex combinations of the elements carbon, 

 nitrogen, hydrogen and oxygen, with the occasional aid of sulphur 

 and phosphorus. These are the elements of that protoplasm which 

 is the physical basis of Hfe, and by their interplay they form the 

 unstable and comphcated groupings of which that remarkable 

 material is composed. All the phenomena we call vital are associated 

 with the change of some protoplasm, and the oxidation of carbon and 

 hydrogen. But it is quite open to question whether the connection of 

 life with the elements first specified is inevitable. We can conceive 

 the existence of similar groupings of other analogous elements 

 forming other protoplasms capable of existing within much greater 

 ranges of temperature than any plants or animals now known to us 

 have to withstand. For example, we can imagine a high temperature 

 protoplasm in which silicon takes the place of carbon, sulphur of 

 oxygen and phosphorus of nitrogen, either wholly or in part. In fact, 

 protoplasm so far as we know it in purest form, always contains 

 some sulphur, and often a little phosphorus, representing a very 

 partial substitution of the kind in question. 



In view of our newer knowledge there is therefore nothing very 

 far-fetched in supposing that under suitable conditions a plant or an 

 animal organism, may be able to construct from silicon compounds, 

 ultimately derived from the soil, something akin to silicon protoplasm 

 for use in its structures. 



You will now ask me whether there is any evidence that anything 

 of this kind actually occurs in Nature. I think there is, although I 

 admit that the evidence is not very varied as far as we know. 



First as to the Vegetable kingdom. It is well known that many 

 plants take up silicon in some form from the soil, and use it in 

 ways which my botanical friends tell me they do not at present 

 understand. Silicon is present in the straw of cereals, such as wheat, 

 oats, etc., and in most of the Graminese. It was supposed that the 

 stiffness of the straw was secured by a siliceous varnish, but this view 

 is not now in favour, as it has been found possible to remove silica 

 from the straw by careful treatment, without diminishing its rigidity. 

 It is also present in the leaves of some palms, for my friend. Dr. 

 Hugo Miiller, in the course of his extensive researches on the sugars 

 present in certain palm leaves, has been much troubled by the presence 

 in the extract from the leaves of siliceous compounds of unknown 

 nature. Again, a well-known substance called "Tabasheer," con- 

 sisting largely of hydrated silica including some organic matter, is 

 obtained at the nodes of some bamboos. What purpose silicon serves 

 in these plants which seem to have special need for it we do not 

 know, but the subject appears to be well worth closer examination 

 than it has yet received at the hands of plant physiologists. 



I have on the table some good specimens of Tabasheer, and can 



2 u 2 



