president's address SECTION D. 117 



confess that, for my own part, I find it very difficult to conceive 

 that every particle of the protoplasm is equally capable of perform- 

 ing these different functions, nor does the necessity of doing so 

 seem so imperative now that we know that a certain degree of 

 organisation is present in cell matter. Becaiise we cannot as yet 

 distinguish differential media of function in the structure of the 

 monoplastids we are hardly at liberty to build theories on the 

 assumption of their non-existence, and conclude that these 

 organisms are exceptions to the otherwise general law of cyclical 

 life. In view of the fact that all nucleated cells, and probably 

 all non-nucleated monoplastids, conjugate and undergo a certain, 

 however slight, change in the molecular arrangement of their 

 protoplasm, a change followed by a period of incubation prepara- 

 tory to the renewal of reproduction by fission, it seems likely that 

 this process is in them, as in the higher organisms, necessary to the 

 reinstatement of life in the vigor of youth, and that were this 

 process prevented they would become incapable of fission and die. 

 The renewal in the offspring of the energy, not exhausted, but 

 diminished in the parent, appears to me to be at least as much the 

 purpose of conjugation as the commixture of heredity coiu-ses and 

 that no less in the protozoa than in the metazoa. The immortality 

 of the former is not potential but incidental to the attainment of 

 matui-ity. A defender of the theory that reproduction is established 

 solely for the purposes of heredity might urge that the higher rate 

 at which vital processes go on in the earlier stages of individual 

 life is not due to a renewal of energy as a primary intention, but 

 that this is the necessary means by which alone tlie product of the 

 fusion of hereditary tendencies can be brought with speed to 

 maturity and so enabled to escape the perils of youthful feebleness. 

 Kapid growth is merely an adaptation brought about by natural 

 selection. But heredity itself is as much a process of utility to the 

 sjDecies as reinvigoration is to the individual ; adaptation, common 

 to both cases, does not affect the real significance of either. On 

 the whole, it is perfectly true that the monoplastids are con- 

 ditionally immortal, but there is not sufficient evidence to show 

 that the condition being unattained, they are not potentially mortal. 

 To these few of the biological themes which have an attraction 

 extending beyond the pale of Science it would have been a pleasure 

 to add that great, and, so far as the public mind is concerned, still 

 unsettled question — the origin of species. Evolution, whether by 

 natural selection or other secondary causes, stands now in almost 

 the same relation to biology as gravitation to astronomy. It is the 

 master key which, in the hands of the expert, is constantly opening 

 to the light the recesses of nature ; it is repeatedly explaining the 

 apparent contradictions and inconsistencies met with in his re- 

 searches; and, above all, it is conferring upon him the power of 

 anticipating discover}' by enabling him to inform us with a very 

 great degree of probability, followed by verification, of otherwise 



