Varietäten, Descendenz, Hybriden. — Physiologie. 167 



Shull, G. H., Color inheritance in Lychnis dioica. (Am. Nat. 

 XLIV. p. 83—91. Feb. 1910.) 



Shull finds that the purple color of Lychnis dioica L. is due to 

 the interaction of three "genes", as in Lathyrus, Matthiola and other 

 cases. Two types of purple occur, a reddish- and a bluish-purple, 

 the former becoming blue when treated with alkalies and the latter 

 changing to red on the addition of weak acids. The bluish color 

 is found to be hypostatic to the reddish, which is the reverse of 

 the condition found in other plants. The cause of this reversal of 

 color relations between bluish and reddish anthocyan, is not yet 

 ascertained. Gates. 



Shull , G. H., Results ofcrossing Capsella Biirsapastoris and 

 Bursa Heegeri. (Proc. 8th int. zool. Congr., Boston, Meeting Aug. 

 19—2-1, 1907. Cambridge, Mass. 1910. Cpp.) 



Capsella heegeri, or Bursa heegerii, is a mutant from C. hursa- 

 pastoris, found wild in Germany in 1900 and described by Solms- 

 Laubach. It differs in the shape of the capsules which are circular 

 instead of flat and triangulär. Shull isolated four types or elemen- 

 tary species of C. bursa-pastoris differing in leaf characters and 

 found that in crossing they behave as a Mendelian hybrid. Reci- 

 procal crosses were tlien made between C. heegeri and the simplest 

 of the four elementary species of C. bursa-pastoris. In this way four 

 elementary species of C. heegeri were produced, the leaf characters 

 of the hybrids showing Mendelian ratios, but the heegeri capsules 

 appearing only in about one plant in 223 of the F.2. Gates. 



Biackman, F. F., Vegetation and Frost. (New Phytologist, VIII. 

 9, 10. p. 354—362. 1909.) 



A summary of the present State of knowledge, based mainly 

 on the recent'publications of Molisch, Mez, Gorke, and Lid- 

 forss. The chief observations and conclüsions of these authors on 

 the freezing of plants are presented briefl}^ and in a form extre- 

 mely useful to those to whom the original papers may not be 

 available. W. G. Smith. 



Brown, W. H. and L. W. Sharp. The closing response in 

 Dionaea. (Bot. Gaz. IL, p. 29-302. fig. 1. April 1910.) 

 A summary of the results obtained from various experiments 

 is as follows: The closing response in Dionaea depends upon the 

 intensity rather than upon the number of Stimuli, the number of 

 Stimuli required varj'ing in the inverse order of their intensitj'. 

 Response is normall}'- brought about by the compression of certain 

 cells at the bases of the sensative hairs but the compression of 

 other cells of the blade also causes closure and it is probable that 

 the latter cells are equall}" sensative with the cells at the bases of 

 the hairs, as is indicated by electrical and thermal Stimulation. The 

 closing response follows the application of mechanical, electrical 

 and thermal Stimulation. It also follows a combination of Stimuli of 

 two kinds when consecutively applied, the individual Stimuli being 

 of an intensity such that either alone would bc insufficient. The 

 effect of mechanical Stimulation is due to compression of cells and 

 not to contact with a hard object, continued pressure or release of 



