328 EXPERIMENT STATION RECORD. 



characters. It is suggested that possibly increase of vigor in hybrids will be 

 found dependent on an aggregate of dominant characters. 



An examination of the theory of factors by the methodical recrossing of 

 hybrids, E. von Tschermak (IV. Conf. Internat. G^netique Paris, Compt. Rend. 

 et Raps., 1911, pp. 91-95, pis. 10). — A test was made of the theory of factors, 

 according to which certain units, acting either independently or in cooperation, 

 give rise to the visible characters of species and races. This theory is held to 

 give a satisfactory explanation both of the production of new forms resulting 

 from hybridization and also of complicated cases of Mendelian inheritance. 



Reduplication of terms in series of g-ametes, W. Bateson and H. C. Punnett 

 {IV. Conf. Internat. Gmetique Paris, Compt. Rend, et Raps., 1911, pp.99, 100). — 

 The authors present a new explanation of the phenomena of coupling and 

 repulsion and state that evidence has been found which proves that these are 

 influences of the same phenomenon and that in each the effects are produced 

 by reduplication of those gametes which represent the parental characters. 



Concerning geographical races with fixed and variable characters, J. V. 

 ViviAND-MoREL {IV. Coiif. Intemat. Gen^tique Paris, Compt. Rend, et Raps.^ 

 1911, pp. 266-274)' — -^ review is given of a study of a large number of Linnsean 

 types of plants indigenous to France and other parts of southern Europe and 

 northern Africa, from which the author concludes that the races which com- 

 pose the original types do not in all cases possess fixed characters. In the case 

 of perennial and shrubby plants they seldom breed true, although in annual 

 species the great majority of such forms reproduce themselves by seed. 



Mendelism and acclimatization, H. Nilsson-Ehle {IV. Conf. Internat. 

 G^netique Paris, Compt. Re7id. et Raps., 1911, pp. 136-157). — The author claims 

 that his experiments with cereals indicate that there is a certain relation be- 

 tween the adaptive changes of plants called hereditary acclimatization and the 

 regrouping of Mendelian factors. Acclimatization is believed to be due to a 

 regrouping of the components or Mendelian factors already existing, resulting in 

 more advantageous combinations. 



"Variation in first generation hybrids: Its possible explanation through 

 zygotaxis, W. T. Swingle {IV. Conf. Internat. Genetique Paris, Compt. Rend, 

 et Raps., 1911 pp. 381-394, figs. 10). — The author describes experiments con- 

 ducted under the auspices of this Department in crossing various Citrus species, 

 and accounts for the variation by the positional relation of the chromosomea 

 He suggests for this supposed positional influence the name zygotaxis, and by 

 this he means the arrangement in the syngamete or zygote of the chromatin 

 and other hereditary substances derived from the parental gametes and the per- 

 sistence of this arrangement in the cells produced by the subdivision of the 

 syngamete. 



Mosaic heredity, L. Blaeinghem {IV. Conf. Internat. Genetique Pans, Compt. 

 Rend, et Raps., 1911, pp. 101-131, figs. 19; alts, in Bui, Soc. Bot. France, 60 

 {1913), 'No. 4, PP' 282, 283). — The author designates as mosaic heredity that 

 method of special transmission by which is manifest in the descendants the 

 corresponding characters of the parents. Attention was first called to this 

 method by Naudin in 1859, and it is said that it offers analogies to alternate 

 and Mendelian heredity. The author describes a number of examples of this 

 form of heredity and discusses their common characters and means for dis- 

 tinguishing them from the so-called graft hybrids. 



A bibliography is appended. 



Is the law of uniformity of hybrids of th.e first generation absolute? M. R. 

 Gaed {IV. Conf. Internat. Genetique Paris, Compt. Rend, et Raps., 1911, pp. 

 197-200). — The author states that although Naudin concluded from his experi- 

 ments that all hybrids derived from a cross resemble each other in the first gen- 



