198 Varietäten, Descendenz, Hybriden. 



organism to environmental Stimuli, both internal and external. All 

 that the organism actually inherits is a certain amount of proto- 

 plasm, endowed with a certain amount of energy, and a certain 

 sequence of environmental conditions. In so far as these are iden- 

 tical in any two successive generations the final result must be 

 identical also, the child must resemble the parent; in so far as 

 they are dififerent the child will differ from the parent, but the 

 differences in environment can not be very great without preven- 

 ting development altogether. 



About the second problem, that of the origin of species, the 

 author says: Species may arise by divergent evolution under 

 changing conditions of the environment, and may become sepa- 

 rated from one another by the extinction of intermediate forms. 

 The environmental Stimuli (including, of course, the body as part 

 of its own environment) may, however act in two different ways: 

 (1) Upon the body itself, at any stage of its development, tending 

 to cause adaptation by individual selection of the most appropriate 

 response, and (2) upon the germplasm, causing mutations or sud- 

 den changes, sports, in fact, which appear to have no direct 

 relation whatever to the well-being of the organism in which they 

 appear, but to be purely accidentaL It seems that mutation has 

 had a great deal to do with the origin of species, though it may 

 have had very little to do with progressive evolution. Similary 

 with regard to hybridization, we know that vast numbers of distinct 

 forms, that breed true, may be produced in this way, but they 

 are simply due to recombinations of mutational characters in the 

 process of amphimixis, and have very little bearing upon the pro- 

 blem of evolution. M. J. Sirks (Wageningen). 



Jones, D. F., Illustration ofinbreeding. (Journ. of Heredity. 

 VI. p. 477—479. 1915.) 



Shows the importance of inbreeding as the quiekest way to 

 make abnormal tendencies visible so that they can be eliminated. 

 The case is one of a race of Leaming corn which had been self- 

 pollinated for three generations and gave albinos in a ratio 3:1, 

 as a simple recessive character. M. J. Sirks (Wageningen). 



Kalt, B., Ein Beitrag zur Kenntnis chlorophylloser 

 Getreidepflanzen. (Zschr. Pflanzenzucht. IV. 2. p. 143—150. 

 1916.) 



In einer Kreuzung von Groninger Wintergerste X Ecken- 

 dorf er Mammut -Wintergerste traten in der Fa-Generation 

 unter 100 Pflanzen 15 weisse auf. Eine Analyse der grünen Homo- 

 und Heterozygoten ergab, dass der Vererbungsmodus dem ein- 

 fachen Mendel'schen Schema C grün c weiss, mit vollständiger 

 Dominanz von Grün folgt, Häufiger wurden Weisslinge unter der 

 Roggensaat gefunden, etwa 50/o, es handelt sich dabei hauptsäch- 

 lich um Saatroggen. 



Die anatomische Untersuchung ergab, dass im inneren Aufbau 

 der Weisslinge kein Unterschied zu dem der grünen Pflanzen vor- 

 handen ist, insbesondere, dass die Chromatophoren, die Träger 

 des Chlorophylls, deutlich vorhanden sind, nur sind sie nicht als 

 Chloroplasten ausgebildet. In einer Arbeit von Miles: A genetic 

 and cytological study of certains types of albinism in maize. 



