BY A. JEFFERIS TURNER, M.D, 45 



concluded to have arisen since this epoch. Sir William 

 Thompson has suggested that living matter in a dormant or 

 spore condition may have been conveyed to the earth by some 

 falling meteorite. If we admit this possibility our difficulty 

 is but pushed further back. There is but one method, that I 

 know of, of meeting the difficulty, and that is by 

 invoking the principle of the " continuity of nature." By 

 an induction, supported by numberless instances, we have come 

 to believe that natural changes come about, not by sudden and 

 violent means, but by the summation of long series of gradual 

 transitions. We can, for instance, trace in thought much of the 

 gradual alteration sustained by our cooling globe as it passed 

 from its primitive molten condition into one suitable for sustain- 

 ing life. We can trace the gradual transitions between living 

 beings. Under their infinite diversity we can trace a funda- 

 mental similarity. The nuclear changes during cell-division, for 

 example, to which I have already alluded, appear to be of a 

 similar character (with some variations in detail) in all animal 

 and vegetable cells, from the most highly organised animals and 

 plants to the lowest. Where we meet with gaps in our 

 classifications, we are accustomed to suppose that these imply 

 the former existence of intermediate forms, which have now 

 become extinct. In this way we may become inclined to believe 

 that the present gap between non-living and living may at one 

 time have been filled by steps of which we are at present 

 ignorant. An attitude of scepticism on this point is reasonable, 

 but if forced to choose between the hypotheses of continuity and 

 discontinuity I should incline to the former. 



This brings me to the end of my task, which has expanded 

 much beyond my original intentions. My object has been not 

 to attempt impossible solutions, but merely to state these 

 problems, as they present themselves to my own mind, as clearly 

 as I could. How far I have succeeded in making myself 

 intelligible is for you to judge. 



