732 TRANSACTIONS OF SECTION K. 



The possibilities of the seed-habit were realised only bit by bit, and the high 

 efficiency of the modern seed depends in large degree upon the close association of 

 other structures which co-operate in its functions. No doubt the first step, the 

 retention of the megaspore, was the most important of all ; though, that this 

 might be effective, some contrivance for the capture of the pollen-grains must have 

 accompanied it. Later steps in the process of seed-evolution would include the 

 adjustment of au intraseminal embryonic stage, and in time the substitution of 

 the pollen-tube for the liberation of vsperms. 



Now assuming, as I think we are entitled to assume, that seeds have come into 

 existence along some such lines as those thus crudely blocked out, there is a great 

 difficulty in conceiving the process other than discontinuous. Every one of the 

 stages emphasised involves the conception of something more abrupt than mere 

 gradual variation. And there is, of course, the old difficulty confronting us as to 

 how the organ or mechanism came to be pre served at its inception. All these 

 difficulties vanish when it is recognised that effective variation is of the discon- 

 tinuous order, and that the successive changes involved may be considerable 

 enough to be designated jumps. Happily such views, based upon experimental 

 results, have been formulated by De Vries in his Mutation Theory. That theory 

 is 80 well known to botanists in this country that any exposition here is quite 

 superfluous. The least thing that can be said in its support is that it is perfectly 

 tenable. But we may go much further than that. Apart from the Theory of 

 Natural Selection, no modern hypothesis of evolution has been so helpful or so 

 likely to stimulate further work. The results of continued investigations in this 

 field, now so actively pursued, will be awaited by all biologists with a keen and 

 sympathetic expectancy. Not the least of the advantages that follow in the wake 

 of the Mutation Theory is the shortening of the time required for the evolutionary 

 process. As the physicist imposes a time limit to the period during which life 

 has been possible on the earth, a working theory that reconciles the demands of 

 the biologist with the physical limitations is decidedly reassuring. In this con- 

 nection it is very interesting to note that Monsieur Grand'Eury, one of the most 

 active and distinguished workers in the field of palseobotany, should have found data 

 supporting the view of mutation.' In tracing the passage of fossil plants through 

 great thicknesses of rock he has been impressed on the one hand with the high 

 degree of permanence of certain forms, and on the other with the suddenness, 

 when the moment came, with which one species passes into another. 



The collection of data of this kind from our own Coal Measures appears to me 

 a very pressing necessity in view of the rapidity with which the coalfields are 

 being exhausted. Indeed the present is an unique opportunity which can never 

 recur, and the chance of systematically utilising it is slipping away. Whatever 

 view one may hold as to the expediency of making exhaustive collections of the 

 recent flora, there can be no two opinions of our manifest duty to ' make hay while 

 the sun shines' in the matter of the coal fossils. Regarded as systematically 

 arranged collections showing how the plants occur in definite localities, the con- 

 tents of most of our museums, as I am assured by competent authorities, are 

 practically worthless. That innumerable specimens of the greatest value are 

 preserved in museums may be readily conceded ; but my point is that these collec- 

 tions have been accumulated without system, and that details of precise locality and 

 horizon are frequently wanting. All this has to be done over again, and I believe 

 local societies working in touch with a central organisation could do a memorable 

 service which would earn them the gratitude of future generations and at the same 

 time provide a fresh outlet for their energies. 



To us the coal industry, with its vast resources, is a convenient mechanism for 

 making fossil plants accessible. The colliery proprietor may be relied on to afford 

 all reasonable fstcilities for the acquisition of select examples from these super- 

 abundant and' embarrassing waste products. Should he incline to go further and 

 contribute towards the modest funds necessary to carry out the undertaking 

 worthily, he would increase the debt which science owes to industry. The 



' Grand'Eury, Compfes Mertdus, tom. cxlii. p. 25. 



