436 Mr Eattray on the Distribution of 



(a) Swarmspores emitted from plants in a medium at the 

 ordinary temperature, germinated more rapidly when trans- 

 ferred to a vessel of water, the temperature of which was 

 raised through 10° Fahr. ; (b) conversely, swarmspores 

 emitted from plants in a medium at a more elevated 

 temperature germinated more slowly when placed in a 

 vessel of water at the ordinary temperature ; (c) swarm- 

 spores placed in a vessel of water whose temperature was 

 frequently (from five to eight times daily) changed through 

 20° Fahr. {i.e., from the ordinary temperature t° to t° -f20° 

 and then back to t°), were not observed to germinate at all. 



Experiments were also made with the view of deter- 

 mining the maximum range of degrees Fahr. through 

 which the temperature might be raised — (a) without being 

 again reduced, and (^) when again reduced, given but 

 varying numbers of times, — x — without resulting in the 

 destruction of the germinating power ; but definite results 

 were not attained, owing to the failure in the supply of 

 swarmspores. At such periods, however, as these can 

 be copiously procured, interesting results may be expected 

 in this connection. 



The effects of modifying the degree of movements of 

 the water in which embryos of plants were growing were as 

 follows : — 



1. Movements of moderate rapidity — 80 to 100 revolu- 

 tions per minute — produced in a uniform direction (right 

 to left or conversely), and especially towards the centre of 

 the vessel, apparently produced no detrimental effect, the 

 movements being repeated for five minutes every half-bour 

 from 9 A.M. to 1 p.m., and again from 2 p.m. to 5.30 p.m. for 

 four weeks. Germination proceeded normally in every way. 



2. Similar movements, generated much more peripher- 

 ally, had a retarding effect in a marked degree, probably 

 because of increased concussion shocks on embryos settled 

 around the margins of the bottom of the vessel as the motor 

 passed nearer to them in its course through the water. 

 The ratio of length of the young plants in the two cases 

 being on the average as 3 : 1. 



3. Irregular movements, resulting from right to left, 

 followed rapidly by left to right courses of the motor, had 

 still more prejudicial effects if the speed of the motor 



