IgIo] SHATTUCK—HETEROSPORY IN MARSILIA 25 
TABLE I 
LIGHT READINGS TAKEN IN OPEN AIR AND IN WATER AT DEPTHS OF 2.5, 5, 
D Ioc™, AND ALSO IN NORTH AND SOUTH ENDS OF GREENHOUSE 
These readings were taken with a solio-paper actinometer and show approximately 
the varying intensities of the light where different cultures were grown. 
UNDER WATER GREENHOUSE 
° r . m m m South “P 
1907 Time Weather Open air |2.5¢™) 5¢™ | roe pn North end 
September 14 | 3:45 clear ee gee Gureoe aaere BOT oe 5 Ao 
tember 20 |12:20-12:40 | clear TO SOCr | tap BO Pe ies 
September 25 | 2: : clear (?) | 20sec. | .. 1... 13§ | fo | ro (shade) 
September 26 | 2:30- 2:40 cloudy 45 sec. By eR ies Bab eo 7o 
The plants in the best lighted positions recovered from the effect 
of transplanting more rapidly and grew much more vigorously than 
those in more subdued light. This was shown by the rate of growth 
of rhizomes, which under the most favorable conditions was as much 
as 12.5°™ daily; while for those in the most subdued light 6°" was 
the maximum daily growth. The color of the plants in good light 
was also a darker green and the thickness of the leaf blades, rhizomes, 
and petioles was also greater. Neither the length of the petioles nor 
the size of the leaves was so great as those of the shaded plants. 
On August 6, the first sporocarps were discovered in tank 5, which 
had been placed in strong light; these were evidently several days 
old and must have been evident as early as August 3. On August 
8, tank 4 showed some sporocarps that had probably been in evidence 
about two days; while in tank 3 the very first indication of sporo- 
carps was noticed. Tank 2 was in diffused light except for about two 
hours in the middle of the day, and while the plants grew well they 
stubbornly refused to fruit either above or below the surface of the 
water. Finally on August 17 some sporocarps were found in this 
tank out of water. These soon turned brown, however, and on sec- 
tioning were found to be blasted. This tank continued to produce 
a few blasting sporocarps for 18 days, but it produced good sporocarps 
4S soon as it was placed in a strong light. 
Influence of water 
It has been observed that Marsilia quadrifolia fruits most profusely 
at the surface or a few centimeters above the surface of the water. 
