18 ANNUAL ADDRESS, MDCCCLXXI. 



of life, have, since the discovery and improvement of the 

 microscope, had to yield this estimate to a whole world of 

 beings, animal and vegetable in nature, of so much minuter 

 character that the zoophytes are veritable giants or even 

 mountains in respects to them. These smallest organisms 

 were at first spoken of collectively as infusoria, and a like 

 warfare prevailed, as in the instance of the corals and 

 sponges, on the question as to whether they were plants 

 or animals, and as to which were plants and which animals. 

 This contest indeed is still undecided with respect to many 

 among them, and it is doubtful whether, with regard to 

 some of them, it can ever be decided. However, the dis- 

 cussions that have prevailed have resulted in the deter- 

 mination of the real nature of a large proportion ; and 

 naturalists concur in recognising two great classes the 

 protozoa and the protophyta i.e. primordial animals and 

 primordial plants. The still doubtful beings are arranged 

 as phytozoa, or plant-animals. 



The diffusion of microscopic organisms has been especially 

 remarked in water, and the teeming of a drop of pond 

 water with life is a phenomenon calculated to arrest the 

 attention of even the casual observer. But water is not 

 the only medium in which they abound, for although the 

 more definite and larger forms are to be found in it, yet 

 we now know that the surface soil and the air also 

 abound in organic germs. 



Prof. Tyndall's expeniments and observations, as recounted 

 in his Lecture on Dust and Disease, take rank among 

 those things calculated to arrest the attention of every 

 thinking individual. Many of you, I doubt not, have read 

 that lecture, either in its entirety, or in abstract as it 

 appeared in the Times newspaper and in several journals. 



