No. 606] SHOETEB ARTICLES AND DISCUSSION 375 



The usual method gives substantially the same result as the 

 long one and a hetter result than the approximate method. From 

 the nature of experimental work, great rejSnement in statistical 

 treatment is often a waste of effort, and without questioning the 

 value of Dr. Pearl's suggestion in cases in which the greatest 

 accuracy is warranted it appears that the simple formula is still 

 adequate for most practical purposes. 



CHARACTERS INDICATIVE OF THE NUMBER OF 

 SOMATIC CHROMOSOMES PRESENT IN 

 (ENOTHERA MUTANTS AND 

 HYBRIDS 



The pollen grains of 28-chromosome (Enothera Lamarckiana 

 gigas de Vries were long ago shown (Lutz, '09 ) ^ to be character- 

 istically 3-f-lobed (chiefly 4-), instead of 3-lobed, as in O. La- 

 marckiana and other diploid forms. Gates has since contributed 

 much to our knowledge of this subject. Recently Bartlett ( '15)-. 

 in discussing the 3 + -lobed condition of the pollen of 28-chromo- 

 some 0. stenomeres mut. gigas, stated that these 3 + -lobed grains 

 "are larger than the triangular grains of the type" (0. stenom- 

 eres). It may be added that the largest, best-appearing 3- of 

 tetraploid forms in general, is larger than the typical, best-ap- 

 pearing 3- of diploid, and the largest, best-appearing 3 -j- - of the 

 former, larger than the typical, occasional 3 4- - of the latter. 

 Smaller 3- and 3 -f- - grains are found in the pollen of both, but 

 they are rarely perfect-appearing, and it is doubtful whether 

 slightly imperfect-appearing grains are capable of functioning. 

 A careful examination of the adult characters of a form, together 



1 Notes on the first generation hybrids of (Enothera lata X 0. gigas, 

 Science, N. S., 29: 263-267. Gates (Pollen <levelopment in hyl.rids of 

 (Enothera' lata X 0. LamarcUana, Bot. Gas., XLIII, 81-115, Feb., 1907) 



2 "The Mutations of (Enothera stenomeres," Amer. Jour. Bot., 2: 100- 



