No. 1, May, 1921] GENETICS 33 



233. Brainerd, Ezra, and A. K. Peitersen. Blackberries of New England. Their 

 classification. Vermont Agric. Exp. Sta. Bull. 217. 84 p., 36 pi. 1920. — A comprehensive 

 report on the classification of the blackberries in which the authors conclude "that it is no 

 longer a question of whether or not new species of blackberries are produced in the wild 

 through natural hybridization but rather that it is a question whether hybridization is not 

 the primary or only factor in the production of new species within this group." A more 

 detailed discussion of the subject of spontaneous hybridization is to be published later but 

 some of the more important facts are enumerated which have led to the conclusion that inter- 

 crossing of different species of blackberries is of common occurrence in the wild: 1. All New 

 England forms show more or less infertility, none having been found 100 per cent fertile, while 

 many almost sterile forms have been grown. This infertility is due largely to the impotence 

 of the pollen. — 2. Intermediate forms between all of the well recognized species exist in the 

 wild. — 3. Wherever an intermediate between any two forms of blackberries is found the two 

 suspected parents usually can be located. — 4. Plants of the blackberry sub-genus are very 

 variable. — 5. Seeds from selfcd flowers of a number of suspected hybrids have been grown 

 and these plants, in the majority of cases, show a reversion to the suppressed parent types. — 

 6. A number of artificial crosses have been effected between different species. The plants 

 from these crosses are almost identical with the suspected wild hybrids. — 7. In more than 30 

 different combinations of New England blackberries that were cross-pollinated, not one 

 failed to produce viable seed. — The authors point out that most of the characters which 

 distinguish the different species of blackberries are quantitative, and the hybrids, therefore, 

 nearly always show an intermediacy in the characters which are present in varying degrees 

 in the parents. The offspring of such hybrids do not show segregation into dominants and 

 recessives in the ordinary Mendelian ratios but all grades of intermediates are found. In 

 some cases (R. permixtus, R. frondisentis, and R. abbrevians Blanchard) these hybrids appear 

 to be more or less fixed. — J. H. Kempton. 



234. Brierly, W. B. Experimental studies in the specific value of morphological char- 

 acters in the fungi. Proc. Linnean Soc. London 1918: 55-56. 1918. — Pedigree cultures were 

 made from single spores of Botrytis. The spore mode of a given culture from cabbage was 

 found to be different when the organism was grown on tomato, and gave other modes for 

 other substrata. A culture derived from onions when grown on cabbage differed in mode 

 from that originating from cabbage. He concludes that the fungus consists of many ele- 

 mentary species or Jordanons which are morphologically distinct. He recognizes a "normal 

 variation," present upon whatever host and characteristic of the elementary species, and a 

 "modal" variation induced by the substratum. In nature the elementary species are usually 

 on special hosts but saprophytically are of broad range. To determine an elementary 

 species it is therefore necessary to isolate it and determine its "modal variation" on a series 

 of standard media. Similar res.ults and conclusions were had with PenicilUum and Stysanus. 

 — F. L. Stevens. 



235. Broman, Ivar. Das sogenannte biogenetische Grundgesetz und die moderne 

 Erblichkeitslehre. [The so-called biogenetic law and modern genetics.] Bergmann: Munchen 

 and Wiesbaden, 1920. 



236. Buxton, L. H. Dttdley. The inhabitants of the eastern Mediterranean. Biometrika 

 13 : 92-112. 1 pi. 1920. — The author deals with physical anthropology of ancient and modern 

 Greeks, examining cephalic index, glabello-occipital length, greatest head breadth, upper 

 facial index, nasal index, stature, and pigmentation. Significant difference in cephalic index 

 between Lycian Greeks (80.27 ± 0.35) and those of Meligala in Messenia (82.49 ± 0.38), and 

 of Cyprus (82.54 ±0.11) are found; also between Cretans (79.26 ±0.16) and Cypriots. High 

 standard deviations indicate mixed population. Variability of Cretans dates from Middle 

 Minoan times. Endogamous Lycian gypsies show standard deviation of cephalic index of 

 only 2.83 ± 0.19. There is no significant difference in coefficients of variation of head length 

 and head breadth for the same group. For different districts head breadth is stable in Cyprus^ 



BOTANICAL ABSTBAfTS, VOL. VIII, NO. 1 



