May, 1920] GENETICS 215 



tissue. In the latter case the c irolla is generally closed and bhi may be considered 



secondary sex character associated with pure femaleness, appearing when maleness is m 

 completely lacking. In a few cases stamens as well as pistils are sterile. So there is every 

 step of variation in which maleness is expressed. Femaleness also varies in the degree of its 

 expression. Classification is impossible. Conclusions: (1) Fundamentally, maleness and 

 femaleness reside in all somatic cells of all Bporophyi ic individuals. (2) Maleness and female- 

 ncss are quantitative differentiations, they are relative; there are all grades of intersexes 

 and all grades of compatibilities. (3) Sex determination at least in hermaphrodites, is fun- 

 damentally a phenomenon of somatic differentiation that is ultimately associated with pro- 

 cesses of growth, development and interaction of tissues and subject to modification or even 

 complete determination by them. — C. A. Gallastegui. 



1518. Swingle, Walter T., and T. Ralph Robinson. Tangelos: What they are. The 

 value in Florida of the Sampson and Thornton tangelos. U. S. Dept. Agric. Bur. Plant Ind. 

 C[rop] P[hysiology] & Breeding] I Investigations] [Circular] 4. 3 p. 1918. — Crosses between 

 the tangerine orange and the grapefruit have been made, producing a new type of fruit named 

 tangelos. The fruits resemble round oranges more than either of their parents and are 

 exceedingly variable. Fruits of sister plants from seeds of a single cross-pollinated fruit are 

 often very unlike. Second-generation seedlings resemble the Fi plant almost as closely as 

 though grown from a bud. — There are now two well recognized varieties of tangelos, called 

 the Sampson and Thornton. The fruit of the Sampson variety is pear-shaped with a smooth, 

 thin pale orange skin and an acid, soft, juicy, deep orange-colored pulp. The fruits vary in 

 size though they are usually larger than an average orange. — The fruit of the Thornton tan- 

 gelo is of a very different type having a rough thick skin with a very pale orange-colored 

 juice. It has little acidity and resembles a good-flavored orange more than it does a grape 

 fruit or a tangerine but resembles the tangerine in having a free rind. — -The success of these 

 two tangelos has led to the creation of hundreds of additional hybrids between tangerine 

 oranges and grape fruit and while all of these have not been thoroughly tested there is reascn 

 to believe that some of them will prove to be resistant to the citrus canker. — /. H. Kempton. 



1519. Tammes, T. De veredeling van het vlas in Nederland. [Flax-breeding in Holland.] 

 Mededeel. Vereen. Wetensch. Teelt Nederland. 9. 19 p. 1918. — Discusses four points rela- 

 tive to flax-culture and flax-breeding: (1) the measures taken in the different flax-growing 

 countries to improve the methods of culture; (2) improvement of technical manufactures 

 of the gathered products; (3) means of propagating flax-growing; and (4) the results thus 

 far obtained in flax-breeding. This last-named subject is the most important in the author's 

 paner; but the other three are also discussed in a most interesting manner. The perpetual 

 propaganda, made by the governments in the different countries, did not yieid any result; 

 flax-disea?es and other circumstances, (as the renewed import of cotton after finishing the 

 American Civil War (1865) were fatal to the flax-culture in many countries (especially in 

 the Dutch province of Groningen). — The scientific method of amelioration, by breeding new 

 and better strains of flax must save the culture; the researches necessary for this work 

 are at present time of great importance. Great difficulties are met: flax-growers make 

 their cultures in a manner that gives always abnormally developed and etiolated plants; 

 these plants are much more feeble and much less resistant to diseases (flax-wilt, etc.). Flax- 

 wilt may be controlled in two ways: (1) By chemical means, none of which are applicable 

 in practice, and (2) by breeding new immune strains. Author has one such immune strain 

 now in cultivation, but this strain has stems too thick and too short for satisfactory use as 

 an economic strain. The so-called "process of degeneration" is of importance; if the grower 

 himself harvests each year the seeds necessary for his cultures in the following year, the 

 cultures grow steadily worse. Each three or four years newly imported Russian seed must 

 be used for sowing to cope with this degeneration. The Russian seed is always a mixture of 

 several types of plants that may be isolated and which give posterities with great differences 

 in hereditable characters. Such a field of flax is not at all a homogeneous culture, but prob- 

 lems of manufacture make homogeneity of great importance. The process of degeneration 



