Vererbung, Variation, Mutation. 297 



du latex n'est pas la meine lorsqu'on l'etudie par coniparaison, dans les diverses 

 parties de la plante. C'est ainsi que la variete dite fingikäkägo donne du 

 latex poisseux ä la base comme au sommet, alors que la variete Mandrianambo 

 ne contient pas, ä la base, de caoutchouc, le latex poisseux etant localise dans 

 les parties les plus elevees de la plante. Les auteurs attribuent ces variations ä 

 la coraposition des latex divers contenus dans la tige, ä Tage, et au milieu. Le 

 bon latex semble provenir principalement du über, mais ceci ne sufflrait pas, 

 d'apres les auteurs, ä expliquer les differences observees, et ils seraient disposes 

 ä admettre l'existence de formes biologiques distinctes. C. L. Gatin. 



874) Manu, A., Coloration of the Seed Coat of Cowpeas. In: Journ. Agr. 

 Research, Vol. II, Nr. 1, S. 33—56, 1914. 



The niorphology of the seed coat and the way in which the pigments are 

 arranged in the various layers was studied in order to discover whether there 

 are any facts bearing on problems of heredity in this form, outside of the mere 

 facts of the different color arrangements themselves. The greatly diversified co- 

 lor schemes of the different varieties of cow-peas are based on two factors: 



(1) An extremely uniform basal color, ranging from very pale yellow to deep 

 copper red, but found to be in all cases due to a melanin-like pigment deposited 

 in the basal-color layer, the differences in tint being unquestionably caused by 

 differences in quantity rather than in character of the pigment present; and 



(2) a superimposition upon this basal color of variously arranged pigment areas 

 in the palisade layer, the outer layer of the seed coat, the pigments here being 

 of only two kinds, first, a melanin-like pigment very generally identical in color 

 and behavior to that found in the basal layer, and, second, an anthocyanin pig- 

 ment, either associated with this or found in separate cells. And further, this 

 anthocyanin pigment may be of a red color, on account of an acid condition, 

 thereby producing various shades of purple and rose; or it may be alkaline in 

 character, thereby producing various shades of blue and black, and these two 

 may be found in the same cells or in some instances in separate cells. Finally, 

 according as only one, or more than one, or all of these pigments sometimes 

 found in the palisade layer are actually present there, and according as they are 

 uniformly distributed throughout its cells or are variously localized in large or 

 small areas of its cells, do we get the remarkably diversified blotching, streaking, 

 speckling, marbling, or monochrome colorations which characterize the different 

 varieties of cowpeas. 



A study of distribution in the palisade cells in some of the varieties show- 

 ed that there is traceable a decided correlation between the morphology of 

 the palisade cells and the suppression of the pigments in these cells. Pearl. 



875) Castle, W. E., Yellow varieties of rats. In: Amer. Naturalist, Bd. 48, Heft 4, 

 S. 254, 1914. 



Refers to a yellow variety oi' Mus rattus found in Egypt in 1910 and since found 

 to be recessive, while in mice the yellow is dominant but can not be obtained in a 

 bomozygous condition. Gates. 



S?6) Gates, R. R. and Thomas, N., A cytological study of Oenothera 



mut. lata and Oe. mut. semilata, in relation to mutation. In: Quart. 



Journ. Micr. Science, Bd. 59, Nr. 4, S. 523—571, 3 pl. and 4 textfig., 1914. 



The authors describe mutants lata and semilata of Oenothera lamarcläana and 



biennis, and one which arose in F 2 from the cross rubricalyx X grandiflora, and 



find that all have 15 instead of 14 chromosomes. Gates has previously described 



