98 REPORT — 1870. 



poses that in hot summers and autumns, sucli as the present, the fissures in the 

 ground, which have proved so fatal this year to the young partridges, swallow up 

 a multitude of seeds, which are restored again to life when the deep strata into 

 which they are thus introduced, and in which they are sealed up as the chasms 

 close up, come in any way to be laid open to the vmimpeded action of the sun and 

 moistm-e. Squirrels, again, and some birds resembling herein the rodent mam- 

 malia, bury seeds and forget to dig them up again ; and it is supposed that they 

 may bury them so deep as to be protected from the two physical agencies just 

 mentioned. Now germination caimot take place in the absence of oxygen ; and I 

 would add that well-sinkers know to their cost how often the superficial strata of 

 the earth are surcharged with carbonic acid. The rival explanation and the less 

 popular (I do not say the less scientific) looks to the agency of transportation as 

 occuning constantly, and sufficing to explain the facts. By accepting this expla- 

 nation, we save ourselves from running counter to certain experiments, some of 

 which were carried out, if I mistake not, under the auspices of this Section (see 

 Brit. Assoc. Reports), and which appear to curtail considerably the time during 

 which seeds retain their vitality, and to multiply considerably the number of con- 

 ditions which must be in force to allow of such retention for periods far shorter 

 than those which have to be accounted for. A better instance of the expediency 

 of checking the interpretations^based merely upon observations, however accurately 

 made, by putting into action experiments, cannot be furnished than by recording 

 the fact put on record by Mr. Bentham, when discussing this question in his last 

 year's address to the Linnean Society. 



" Hitherto direct observation has, as far as I am aware, only produced negative 

 results, of which a strong instance has been communicated to me by Dr. Hooker, 

 In deepening the lake in Kew Gardens they imcovered the bed of an old piece of 

 water, upon which there came up a plentiful crop of Typha, a plant not observed in 

 the immediate vicinity ; and it was therefore concluded that the seed must have been 

 in the soil. To try the question, Ur. Hooker had six "V\^ard's cases filled with some 

 of the soil remaining uncovered close to that which had produced the Typha, and 

 carefully watched ; but not a single Typha came up in any one of them. (Note 

 in President's Address, May 24th, 1869, p. Ixxii of Linnean Society's Proceedings.) 

 ■ To this I would add that experiments with a positive result, and that positive 

 result in favour of the second hypothesis, if hypothesis it can be called, are being 

 constantly tried in our colonies for us, and on a large scale. I had taken and written 

 here of the Polygonum aviculare, the " knot " or " cowgrass " — having leanit, on the 

 authority of Dr. Hooker and Mr. Travers (see Natural-Histoi-y Re\aew, January 

 1864, p. 124, Oct. 1864, p. 619), that it abounds in New Zealand, along the roadside, 

 just as it does in England — as a glaring instance, and one which would illustrate the 

 real value of the second explanation even to an unscientific man and to an unassisted 

 eye. But on Satui-day last I received by post one of those evidences which make 

 an Englishman proud in thinking that whithersoever ships can float thither shall 

 the English language, English manners, and English science be carried, in the 

 shape of the second volume of the Transactions of the New-Zealand Institute, 

 full, like the first, from the beginning to its last page with thoroughly good mat- 

 ter. In that volume, having looked at the table of its contents, I tm-ned to a 

 paper by Mr. T. Kirk on the Naturalized Plants of New Zealand, and in this, at 

 p. 142, 1 find that Mr. T. Kirk prefers to regard the Poli/f/onum aviculare of New 

 Zealand as indigenous in New Zealand. Hence that illustration which would have 

 been a good one falls from my hands. And I must in fairness add, that because 

 one agency is proved to be a vera causa, it is not thereby proved that no other can 

 by any possibility be competent simultaneously to produce the same effect, what- 

 ever the Schoolmen with the law of Parsimony ringmg in their ears may have said 

 to the contrarj'. I have dwelt upon this subject at this length with the pui-pose of 

 showing how much diiEculty may beset the settlement of even a comparatively 

 simple question which involves only the use of the unassisted eye, or at most of a 

 simple lens. The a fortiori argument I leave you to draw for j'ourselves,' with the 

 simple remark that the question of spontaneous generation is now at least one to 

 be decided by the microscope, and by the employment of its highest powers in 

 alliance with other apparatus of all but equal complexity. 



