78 BOTANICAL GAZETTE [yuLy 
Miss Tammes® has also studied the periodicity in the occurrence of super- 
numerary leaflets in Trifolium pratense quinquefolium DeVries. She finds that 
there are two concurrent anomalies, namely, a division of the lateral leaflets and 
a division of the terminal leaflet. The former is much the more frequent and 
reaches its maximum development below the middle of the primary branches, 
while the latter reaches its maximum also on the primary stems but on the upper 
half near the inflorescence. Few supernumerary leaflets occur on branches of 
second; third, and fourth orders.—G. H. SHULL. - 
Luxsurc’ has presented some experimental data and a very able discussion 
to show that our views of the distribution of growth in geotropically stimulated 
organs, based largely on the experiments of SACHs, are no longer tenable. After 
applying more approved methods in a reinvestigation of the results obtained 
by Sacus and Nott especially, he finds it no longer permissible to regard any 
position as leaving the organ insensible to the geotropic stimulation. The thesis 
maintained by Nort that the normal vertical position of an organ furnishes 
it a condition of indifference to geotropic stimulation is regarded by the author 
ass striking example of the overestimation of the value of curvature reactions 
as indicators of the perception of stimulation by gravitation. The absence of 
@ curvature response by no means implies that the stimulus is not perceived. 
HERING’s results with inverted organs are regarded as rendering a perception 
in the erect position very probable; the absence of a curve means merely that an 
asymmetrical growth was not induced. The author advances the theory that 
se pense Sia by two different but as yet not separately 
concn foes ie “i ST operation involves an alteration in the bigs: 
i a, ma . etric stribution of growth, That favorable objects 
observed is regarded esa ap processes ordinarily combined may be separately 
sbiGs-dis a orice ck sth . The theory advanced is supported 
inate ao alge? or which a resumption growth is a prerequisité 
Wik oa es — % Fi in the Position of normal equilibrium, in 
uinhtNte Acts dak wnaccl 6 ae is to be distinguished from that in which 
1 esis cat sae: that an asymmetrical distribution of gro 
besacuees 1s not induced.—Raymonp H. Ponp. 
Correns® has published ten letters written by Grecor MENDEL to CARL — 
period of MENDEL’s greatest activity in the study of hybrids 
GELI was the recognized authority on Hieracium hybrids in 
NDEL wrote him careful accounts of the progress of his experi i 
NAGELI during the 
(1866-1873). Na 
nature, and Mex 
© TamMeEs. TNE, Ein Bei 
. ; trag 
DeVries. Bot. Zeit. 62:21 1-225. 
7 Luxsure, 
geotropistischen i aoa, Untersuchungen iiber den Wachstumsverlauf bei ef 
egung. Jahrb. Wiss. Bot. 41 >399-457. 1905. 
zur Kenntn’ss von Trijotium pratense quinquefolium — 
1904. 
