262 



NEW PLAXTS NOW COMMON. 



Out of the thirty-five new arrivals, the following nine have taken the 

 county by storm — that is, they are now very common : 



Arenaria serpyllifolia. Lactuca scariola. 



Croton monanthogynus. Melilotus alba. 



Dysodia chrysanthemoides. Plantago Virginica. 



Chrysanthemum leucanthemum. Plantago lanoeolata. 



Lithospermum arvense. 



Some evolution among cacti. By John M. Coulter. 

 [Abstract.] 

 The nascent tubercles of Eumamillaria, Corijpliantha, Echinocactus, Ana- 

 halonium and LopJiophora, show in their generic characters perfectly inter- 

 grading characters, which serve to clear up certain homologies and rela- 

 tionships. 



PHYSICS AND CHEMISTBY. 



Permanganic acid. By Thos. C. Van Nuys and Sherman Davis. 



It is the purpose of this investigation to work out, if possible, I. Tht 

 exact conditions under which permanganic acid or its salt undergoes spon- 

 taneous decomposition. II. Whether it is effective as an oxidizing agent 

 in the decomposition of organic matter. 



I. For determining the exact properties of the acid or its salt, the fol- 

 lowing plan was adopted. Glass tubes, about 30 mm. and 30 cm. long 

 were sealed at one end and carefully annealed. They were then filled 

 with a strong H2SO4 sol. of potass, pernjanganate and heated to 100°C. for 

 12 hrs. This treatment completely removed any organic matter adhering 

 to them. The distilled water was purified by boiling a strong H2SO4 sol. 

 of potass, permanganate, with a condensing apparatus, for some time and 

 then distilling the second time with KMn04. The ]^aOH used in making 

 the standard alkali sol. was prepared from the pure metal and abso- 

 lutely pure water. The tubes were then carefully rinsed with the C. P 



