THE president's ADDRESS. 353 



kind, however, we may safely assert, I think, that the Monera, 

 in the true sense of the word, do not exist. There are certainly 

 organisms in which the chromatin-substance is not organised into 

 a definite nucleus, meaning thereby a body of a certain degree of 

 complexity of structure and co-ordination of parts ; but we know 

 of no organisms in which the chromatin-substance is absent alto- 

 gether. The impression which I derive, rightly or wrongly, from 

 the study of organisms of a simple type of body -structure is that 

 those with abundant cytoplasm, such as amoebae, are far from 

 representing the most primitive type of living beings, speaking 

 generally. Comparison of different forms of life, so far as I am 

 acquainted with them, seems to me to indicate as the most primi- 

 tive type not a relatively large cytoplasmic organism, but an 

 extremely minute bodj', a tiny speck of chromatin. 



Having now enunciated my views, or perhaps I should say 

 confessed my heresies, with regard to the primary form of life, 

 I will now proceed to discuss its possible origin. I need hardly 

 point out that this is a matter in which it is absolutely impossible 

 to arrive at any certain conclusion. Our data are far too limited 

 in every direction. All that is possible is to indicate the limita- 

 tions of the problem, to put forward and discuss possible solutions 

 of it, and to consider which of the solutions has, in the present 

 state of our knowledge, the greatest degree of probability. Do 

 not let us forget that a future generation, with increased know- 

 ledge and a wider outlook, will probably make merry over our 

 efforts to solve an insoluble problem, just as we are apt to do 

 over the speculations of our forefathers. 



At the beginning of this discussion I may lay down two 

 propositions which may serve to confine our speculations and 

 theories within definite limits. 



Proposition I. Life does not originate on our globe at the 

 present time. 



This is the well-known problem of spontaneous generation, of 

 biogenesis and abiogenesis. It is a negative proposition, and 

 therefore one which can only be rendered highly probable but 

 can never be proved, speaking from a strictly logical point of 

 view, since a single instance of life originating de novo and not 

 from pre-existing life would at once upset the generalisation. 

 The evidence for the truth of the proposition may be summarised 

 briefly as follows : On the one hand, it has often been asserted 



