No. 2, September, 1921] 



GENETICS 



123 



Pi cf X wf ; Fi intermediate (in general the non-brittleness of cf dominant) 



F, 



F, 



of 

 3 



2 segregate, cf : wf = 3 : 1 

 1 constant 



This is explained on a bi-factorial basis on presence and absence theory as "wild-form" 

 (A BAB) and "cultivated-form" (abab), or on association-dissociation difference in relation 

 to 3 mutually present factors, where "wild-form" is A'^B'^C and "cultivated-form" is 

 aIbIC.— C. E. Leighty. 



771. VooTHERR, Karl. tJber die theoretischen Grundlagen des VariabilitSts- und 

 Deszendenzproblems. [On the theoretical fundamentals of the problems of variation and de- 

 scent.] Zeitschr. Indukt. Abstamm.- u. Vererb. 19: 39-72. 1918. — In his introduction the 

 author claims that whereas empirically great progress has been made with experiments in 

 which species of animals have been modified into others by changing external conditions, 

 the theory is still backward, and the strife between the Lamarckians and Darwinists is con- 

 tinued with the old blunted weapons. He is greatly impressed by Tower's classical experi- 

 ments on the production of new species of potato beetles by experimental conditions and by 

 Kammerer's work on Alytes, which he thinks prove the possibility of evolution in organisms. 

 Both in inorganic objects and in organisms atypical and typical forms can be distinguished. 

 Typically formed natural objects do not follow external influences but internal laws There 

 are no completely typical natural obj ects. The real task of the naturalist is to find the typical 

 among what happens. — Variation can be caused by changes in external conditions or can be 

 also combined with a change in the internal plant. The author calls these 2 kinds of variation 

 homotypical and heterotypical. — The causes for all variations are changes in the environment. 

 The lines according to which the phylogenetic development will proceed are potentially de- 

 termined and unchangeable. — According to Vogtherr it is illogical to demand that the changed 

 character shall continue after the conditions which caused them have changed back to the 

 original ones. Putting the organisms back into normal conditions is a second experiment 

 on heredity, and a change of the characters back to normal constitutes a second, additional 

 proof, not a refutation. There is no reason to expect that heterotypical variation will be 

 irreversible. The author introduces a "vital force" (Lebenskraft). This vital force reacts 

 upon external conditions. That part of the paper in which the author defines his standpoint 

 as not being quite that of either Driesch, Kant, or Schopenhauer should be read in the 

 original. — The cause of physical things can never be psychical. It is fundamentally impossi- 

 ble to find a scientific explanation of the harmony which we observe in organisms, because 

 the organizing principles are the forces of the organic nature. This harmony is not historically 

 developed, but it has always existed and will exist eternally. — A. L. Hagedoorn. 



772. Waardenburq, P. J. [Dutch rev. of: Behr. Die Heredodegeneration der Makula. 

 (Heredodegeneration of the macula.) Klin, Alonatsbl. Augenheilk. 65: 4G5. 1920.] Genetica 

 3:88-91. 1921. 



773. Waardenburg, P. J. [Dutch rev. of: Briggs, H. H. Hereditary congenital ptosis 

 with report of 64 cases conforming to the Mendelian rule of dominance. Amer. Jour. Oph- 

 thalmol. 1919:408. 1919.] Genetica 3: 65-GG. 1921. 



774. Waardenburg, P. J. [Dutch rev. of: Fleischer, Bruno. tJber myotonische 

 Dystrophia mit Katarakt. (Myotonic dj'strophia and cataract.) Arch. Ophthalmol. 96: 

 91-133.1918.] Genetica 3: 91-96. 1921. 



775. Waardenburg, P. J. [Dutch rev. of: Traquair, H. M. Hereditary glioma of the 

 retina. British Jour. Ophthalmol. Jan., 1919.] Genetica 3: 81. 1921. 



BOTANICAIi ABSTRACTS, VOL. IX, NO. 2 



