268 GENETICS [Box. Absts., Vol. X, 



1744. Rawitscher. [German rev. of: Saito, Kendo, und Hirosuke Naganaski. 

 Bemerkungen zur Kreuzung zwischen verschiedenen Mucor-Arten. (Notes on a cross between 

 different species of Mucor.) Bot. Mag. Tokyo 29: 1915.] Zeitschr. Bot. 13: 646. 1921. 



1745. Renner, O. [German rev. of: Lehmann, Ernst. Zur Terminologie und Begriffs- 

 bildung in der Vererbungslehre. [Terminology, and formation of genetical concepts.] Zeitschr. 

 Indukt. Abstamm. u. Vererb. 22:236-260. 1920.] Zeitschr. Bot. 13: 661-665. 1921. 



1746. Saunders, E. R. On a graded series of forms in Matthiola. Rept. British Assoc. 

 Bournemouth Meeting 1919-1920: 339. 1920. — In addition to hairy and glabrous types of 

 M. incana, there is a rare intermediate type, '*half -hoary." Crosses between "half-hoary" 

 and glabrous give an intermediate hybrid. This, together with its parents and the common 

 hairy type, forms a graded series as regards hairiness, the range of 1 grade overlapping the 

 next. Each grade has a distinct genetic behavior, explicable on the assumption of multiple 

 allelomorphs. — Merle C. Coulter. 



1747. Savelli, R. Apomissia ed ibridisazoni difficili in Nicotiana. — Nota preventiva. 

 [Apogamy and difficult hybridization in Nicotiana. Warning.] Bull. Soc. Bot. Ital. 1920: 

 22-30. 1920. — The author notes the occurrence of apogamy, parthenocarpy, and phenospermy 

 in Nicotiana and comments on their significance in hybridization. Parthenocarpy, accom- 

 panied by formation of some viable seeds, was observed in various forms of N. rustica when 

 only a few castrated flowers were left on plants, but no instances of it were found in trials 

 of several forms of A''. Tabacum. In cases of easy hybridization apogamy need not be con- 

 sidered because development of many fertilized ovules makes conditions for it unfavorable, 

 but when hybridization is diflBcult fertilization of some ovules may result in stimulating 

 adjacent ones to develop without fertilization. Thus, seed secured from N. rustica pol- 

 linated with N. Tabacum produced both hybrid individuals and plants exhibiting purely 

 maternal characters. In wide crosses, such as species of Nicotiana with Petunia, Verhascum, 

 etc., any seed produced is the result of apogamy. The author disagrees with Splendors 

 (Catalizzatori o stimolanti fecondativi e mutamenti in Nicotianae. Bull. Tec. Colt. Tab. 

 Scafati 1-2. 1915), who attributes such cases to "stimulative fertilization." The author's 

 evidence shows, in addition to parthenocarpy, occasional crosses in which some viable seeds 

 were produced, but these always yielded plants having purely maternal characters. Splendore 

 obtained from A''. Tabacum with Verbascum pollen plants of 3 types, viz., intermediate, 

 maternal, and paternal, but repeated trials of this cross by the author yielded no viable seed. 

 The importance is emphasized of studying apogamy in cases of difficult hybridization, and 

 it is pointed out that, although Mendel's law provides a satisfactory explanation of results 

 of varietal crosses, very little is known of phenomena involved in hybridization of different 

 species and genera. — R. E. Clausen. 



1748. Schmidt, Johs. Racial investigations. III. Experiments with Lebistes reticulatus 

 (Peters) Regan. Compt. Rend. Trav. Lab. Carlsberg 14^: 1-8. 1919. — The character ex- 

 amined is the number of rays of the dorsal fin, which varies from 5 to 8. The investigation 

 consists of: (1) Experiments in which the mother is subjected to different temperatures 

 during the various periods of gravidity, and which show that the number of raj's in the off- 

 spring is distinctly influenced by the temperature to which the mother has been exposed; 

 and (2) experiments in which the various mothers are subjected to the same environmental 

 conditions, being in the same aquarium, at a constant temperature. There appeared to be 

 a great difference (about 1 : 2) between the average number of rays in the offspring of mothers 

 with 6 and 8 rays, respectively. — Though the number of organs is influenced by environment 

 there are differences of an inheritable quality between the various individuals. The racial 

 differences in fish are genotypical as well as phsenotypical. — Vilh. Ege. 



