22 ANNUAL ADDRESS, MDCCCLXXI. 



arrive at a point where the senses fail us, and only in- 

 ductive inferences, in which the imagination exercises no 

 mean part, are to be had ; and that well debated problem 

 obtrudes itself, whether organic life is spontaneously gene- 

 rated ; whether new beings can come into existence de 

 novo without the aid of previous organisms or of their 

 germs. 



This vexed question I leave you to form your own 

 opinion upon, according to the evidence that may be 

 placed before you. Suffice it that I have indicated, how- 

 ever imperfectly, another phase of operations of the smallest 

 created beings. 



The diffusion of infusoria throughout the world, where- 

 ever moisture and water are found, and to a greater or 

 less extent mostly in a latent mode of existence, in an 

 encysted form, and in germs, in dry soil and floating in 

 the atmosphere, is a well recognised fact, and one im- 

 mediately realised by the mind. But that such tiny crea- 

 tures should contribute in no small degree to the building 

 up of the crust of the earth, both at remote epochs and 

 also at the present day, is a fact that at the first blush 

 appears startling. Investigation, however, at different parts 

 of the earth's surface and by soundings over the bottom 

 of the ocean have demonstrated the truth of the fact 

 referred to. 



This result is brought about by forms of microscopic 

 life which possess an external coat or shield of silicious 

 or of calcareous matter, and which, consequently, from 

 the weight of their armour, tend to subside to the bot- 

 tom of the water in which they occur. Two groups of 

 beings invested with cases of mineral consistence are dis- 



