80 GENETICS [Bot. Absts., Vol. IV. 



ment of Mendelian heredity is taken from Punnett's Mendelism. "Mendelian segregation is 



not in itself a constructive process. It is a distributive agency The central 



question of evolution comes finally to be the origin of the heritable mutations. Of this as 

 little is positively known at the moment as the constitution of the protoplasm that gives rise 

 to them."— Geo. H. Skull. 



527. Bower, F. O., J. G. Kerr, and W. E. Agar. Lectures on sex and heredity delivered 

 in Glasgow, 1917-18. 16 mo., vi + 119 p., 49 fig. Macmillan Co. : London. 1919. 



528. Brierlt, W. B. Some concepts in mycology — an attempt at synthesis. Trans. Brit- 

 ish Mycol. Soc. 6: 204-235. 1919— See Bot. Absts. 4, Entry 1061. 



529. Calkins, Gary N. Uroleptus mobilis Engelm. II. Renewal of vitality through 

 conjugation. Jour. Exp. Zool. 29:121-156. 1 fig., 1 diagram. Oct. 5, 1919. — In his second 

 contribution on Uroleptus mobilis author finds that the protoplasm of a single specimen and 

 its progeny exhibit a progressive decrease of vitality (as measured by fission rate) and final 

 death if conjugation and endomixis (parthenogenesis) is prevented. In his experiments, 

 conjugation was prevented by the maintenance of isolation cultures. Endomixis was known 

 not to take place because no specimens encysted in these isolation cultures, and in this species, 

 endomixis takes place only at a time of encystment. The results of the paper indicates 

 clearly that a restoration of full metabolic activity follows the conjugation of two closely 

 related individuals of one of these "degenerated" lines. In regard to the effect of encyst- 

 ment and its accompanying asexual reorganization, author believes that, "so far as the evi- 

 dence thus far obtained is concerned, it appears that the initial vitality after encystment and 

 parthenogenesis is as great as, or even greater than, that after conjugation." It is not 

 known, however, whether this high potential is as enduring as that obtained from conjugation. 

 —W. H. Taliaferro. 



530. Carle, E. Premiers travaux sur la selection des riz du laboratoire d'etude des 

 cereales a Saigon. [First work in selection of rice at the Saigon laboratory for the study of 

 cereals. Bull. Agric. Inst. Sci. Saigon 1: 74-87. 1919. 



531. Carrier, L. A reason for the contradictory results in corn experiments. Jour. 

 Amer. Soc. Agron. 11 : 106-113. 1919. — Author's purpose is to show that the common methods 

 of variety testing and related field experimentation with maize are unreliable on account of 

 xenia effect upon size and weight of kernel through cross-pollination. The author's own 

 experiments in planting separately seed of several different strains of certain varieties as 

 compared with mixed lots of seed of these same strains indicate a marked increase in yield from 

 the mixed planting, the result being attributed to this xenia effect. This is supported by 

 experimental evidence of certain other investigators. The author recommends for practice 

 that farmers select their seed corn after the well established types of their respective locality 

 introducing occasionally seed of same variety, but from an unrelated strain brought in from 

 an outside source. — L. H. Smith. 



532. Castle, W. E. Does evolution occur exclusively by loss of genetic factors. Amer. 

 53: 555-558. Nov.-Dec, 1919. — A recent statement of belief by Duerdex (Amer. Nat. 



53:312) that selection can be effective only in the direction of degeneration of a character,, 

 made in connection with wing and toe characters of the ostrich, is criticized by the author. 

 Among other considerations, the latter cites his successful use of selection both in increasing 

 and in decreasing the amount of white in hooded rats and in recovering an ancestral fourth 

 toe on the hind feet of guinea-pigs. — Sewall Wright. 



533. Castle, W. E. The r61e of selection in evolution. An agency for the elimination of 

 variations. Sri. Amer. Supplem. 87:60-67, 00-91. 1919. — Selection as a factor in evolution 

 is discussed and its relation to various theories analyzed. No real diversity of views regard- 

 ing selection exists, but only concerning nature of material upon which it works. Author 



