Varietäten, Descendenz, Hybriden. — Physiologie. 323 



Brainerd, E., The evolution of new forms in Viola through 

 hybridism. (Amer. Nat. XIV. p. 229—236. 1910.) 



The polymorphism of the Violets, which has long been known, 

 is found to be largely due to the occurrence of natural hybrids. 

 About 66 spontaneous hybrids have been discovered, the large 

 majority of which have been shown to segregate in their offspring, 

 giving Mendelian behavior in regard to various characters, such 

 as leaf-shape, pubescence, and seed-color. The hybrids are recogniz- 

 able, not only by the motley character of their offspring, but by 

 their infertility or complete sterility. Another class of anomalous 

 violets which occur sporadicall}'', is believed to be the result of 

 hybridism in the remote or more recent past. Their characters are 

 also usually a mixture of those in some two of the species with 

 which they grow. A number of cases are cited, in which putative 

 natural hybrids have been shown to segragate in Mendelian fashion 

 in their offspring, giving forms with the characters of the parental 

 types. R. R- Gates. 



Spillman, W. J., Mendelian phenomena withoutdeVrie- 

 sian theory. (Amer. Nat. XLIV. p. 214—228. 1910.) 



Variations are classified into four types, 1. Mendelian recom- 

 bination of characters, 2. non-heritable fluctuations, 3. deVriesian 

 mutation, due to irregularities in the distribution of chromosomes, 

 4. variations due to fundamental changes in the germ plasm. The 

 last is regarded as the most important factor in evolutionary change. 

 It is shown that Mendelian phenomena, such as in crosses between 

 red and white sweet peas, can be accounted for without the unit 

 character hypothesis, by supposing that each pair of chromosomes 

 takes part to a different extent in the production of any character 

 of the organism. Thus, if a given pair of chromosomes in the sweet 

 pea functions less actively in the synthesis of the enzyme necessary 

 for the production of red, the plant would produce only white 

 flowers. Explanations of cryptomeric and heterozygous characters 

 are given similarly, on the basis of quantitative differences in the 

 functional activity of certain chromosomes. It is suggested that a 

 pair of Mendelian unit characters should therefore be called a 

 "character differential" instead of character pair; and it is proposed 

 to call "any organ, tissue, substance or cell organ" which has the 

 power of influencing development, a teleone. A Mendelian unit 

 character difference is thus not two unit characters, nor the pre- 

 sence and absence of a Single unit character, but a difference 

 between two teleones. R. R. Gates. 



Andre, G., Sur le de veloppement d'une plante bulbeuse. 

 Variations du poids de la matiere seche. (C. R. Ac. Sc. 

 Paris. CL. p. 545. 28 fevrier 1910.) 



Des oignons ont ete places dans une terre riche en Clements 

 nutritifs; aucun d'eux ne s'est vide; tous ont continue ä grossir re- 

 gulierement malgre l'apparition des fleurs et des fruits. L'auteur 

 etudie ce phenomene de nutrition au point de vue des variations de 

 poids que subissent la matiere seche, l'azote, les cendres totales et 

 leurs Clements, aussi bien dans la partie aerienne que dans la par- 

 tie souterraine de la plante. H. Colin. 



