1893.] Experiments in Germination. 335 



bending could be proved to occur within fifteen to thirty minutes, if 

 bright sparks were supplied at the rate of only one per minute. 

 The most extreme sensitiveness that I have observed in these experi- 

 ments was that of perceptible bending after half-an-hour's exposure 

 to electrical sparks following one another at the rate of fifty in an 

 hour. This result would appear to indicate that in heliotropism 

 under flashing light there need be no summation or " staircase 

 effect " ; but that each flash or spark may produce its own effect 

 independently of its predecessors or successors. 



IV. It is noteworthy that, while the heliotropic effects of flashing 

 light are thus so remarkable, they are unattended with the formation 

 of any particle of chlorophyll. In the many hundred pots, and there- 

 fore many thousands of plants, which have passed under my observa- 

 tion in this research I have never seen the slightest shade of green 

 tingeiiig the etiolated seedlings which had bent towards flashing 

 light. On one occasion I kept a stream of 100 sparks per second 

 illuminating some mustard seedlings continuously for forty-eight 

 hours ; and although this experiment was made for the express 

 purpose of ascertaining whether any chlorophyll would be formed 

 under the most suitable conditions by means of flashing light, no 

 change of colour in any of the seedlings was produced. 



With the exception of those mentioned in the last paragraph, all 

 these results were obtained by using sparks from the coil condenser, 

 AS above explained. These sparks were very brilliant, and yielded the 

 maximal results, which alone are here recorded. 



V. " Experiments in Germination." By G. J. KOMANES, F.R.S. 

 Received October 2, 1893. 



The primary object of these experiments was to ascertain whether 

 the power of germination continues in dry seeds after the greatest 

 possible precautions have been taken to prevent any ordinary pro- 

 cesses of respiration for practically any length of time. 



The method adopted was to seal various kinds of seeds in vacuum 

 tubes of high exhaustion, and after they had been exposed to the 

 vacuum for a period of fifteen months to remove them from the 

 tubes and sow them in flower-pots buried in moist soil. In other 

 cases, after the seeds had been in vacuo for a period of three months, 

 they were transferred to sundry other tubes respectively charged with 

 atmospheres of sundry pure gases or vapours (at the pressure of the 

 air at time of sealing) ; after a further period of twelve months 

 these sundry tubes were broken, and their contents sown as in 

 previous case. In all cases, excepting that of the clover, the seeds 

 .sown were weighed individually in chemical balances, and seeds of 



