abstracts: botany 491 



every case to within 1 part in 500. The accuracy of these values was 

 confirmed bj r analysis of specially purified potassium permanganate 

 crystals and by additional experiments upon the reduction and reoxi- 

 dation of permanganate solutions. Comparative analyses of the Bureau 

 of Standards manganese ore, as well as other ores, showed that the 

 tendency of many of the commercial methods is to yield high results 

 for manganese. 



The bismuthate method is recommended as equal or superior to 

 any other known methods for the determination of manganese, whether 

 present in large or small amounts. W. B. 



BOTANY. — The branching habits of Egyptian cotton. Argyle McLach- 

 lan. Bulletin Bureau of Plant Industry No. 249. 1912. 



The relationships of the two kinds of branches of Egyptian cotton 

 are discussed. Vegetative branches are borne either in or outside the leaf 

 axils at the lowest ten nodes or so of the main axis and are frequently 

 nearly as large as the axis in actual length and in number of nodes. 

 They do not bear flower buds, but, like the main axis, bear fruiting 

 branches. 



Fruiting branches are borne outside the axil at each node of the 

 main axis, beginning at about node 12 from the base; they are shorter 

 than vegetative branches, being only 6 to 8 nodes long; bear a flower 

 bud at each node opposite a leaf, and are further distinguishable by the 

 long basal internode. Fruiting branches borne by vegetative branches 

 are termed secondary fruiting branches. Seemingly axillary fruiting 

 branches occur on the main axis and on fruiting branches. It has 

 been suggested that the first mentioned are secondary fruiting branches 

 of axillary vegetative branches themselves suppressed. 



A large vegetative branch and a fruiting branch never occur to- 

 gether at a node in Egyptian cotton. The further facts, that a vege- 

 tative branch sometimes replaces a fruiting branch; that branches of 

 intermediate form with long basal internode, robust growth and no 

 flower buds occur infrequently in the places of fruiting branches; and 

 that cases of fruiting branches as low as node 5/ or 6 of the main axis 

 have been observed indicate that homology may exist between large 

 basal vegetative branches and fruiting branches, rather than between 

 the large basal vegetative branches and axillary vegetative branches 

 of smaller size which sometimes occur with fruiting branches. A few 

 nodes on the main axis above the basal vegetative branches but below 

 the fruiting branches usually bear no branches, but sometimes pro- 

 duce abortive branches or branches of an intermediate nature. 



