Page:Popular Science Monthly Volume 84.djvu/139

reference number anchor for 23 is not listed in the original, so I placed it at the top of the page.— Ineuw talk 14:43, 13 January 2014 (UTC) (Wikisource contributor note)

^[1] In these experiments the seeds were all carefully examined to make sure that they were perfectly developed^[2] and differed only in size.^[3] The biometric constants of 28 series which developed into mature plants have been compared with those for the original series of seeds from which the plantings were drawn.^[4]

Diagram 2. Differences in Mean Weight of General Population of Seeds and of those which Produce Plants. All differences are reduced to a percentage basis.

The results of these studies can be most conveniently presented graphically. To demonstrate more clearly to the eye the existence of a

done on too small a scale to be conclusive. Possibly among these writings some records of the viability of seeds of different sizes may be found.

1. J. Arthur Harris, "On Differential Mortality with Respect to Seed Weight Occurring in Field Cultures of Phaseolus vulgaris," Amer. Nat., 46: 212-225, 1912.
2. Unfortunately many students of seed weight in its relation to viability or productiveness have not distinguished between small but perfectly developed seeds and those which are blighted or shriveled and immature. It is not at all unlikely that very different results will be secured from the two sorts.
3. Weighings were made of each seed in units of .025 grams, that is, 0.000-0.025 grams = 1 unit, 0.025-0.050 = 2 units, etc.
4. Since the seeds were taken quite at random any stringent selective mortality will be seen in the differences between the constants of the original bulk of seeds weighed and those of the sub-samples planted which actually developed to maturity. The method might not be adequate for a very low selective death rate. In any case it must be expected to give irregular results. A much more satisfactory method is to draw the comparisons between the constants of the seeds which died and the constants of those which developed. Appropriate data for field culture series are being collected. Large greenhouse cultures in sand in which the comparisons can be made between the seeds actually developing and those failing to develop fully substantiate the conclusions drawn from field tests.