5^ BOTANICAL GAZETTE. 



Vitality of the seeds ok Pinus contorta. — How long pine 

 seeds retain their vitality when inclosed in the serotinous cones which 

 sometimes occur on certain species, has probably never been very 

 carefully noted. In 1874, Dr. Engelmann collected in Colorado a 

 branch of Pinus contorta, to which were still persisting the closed 

 cones which had ripened in 1873-72-71-70-69-68-66-65. In the 

 spring of 1879, four years and a half after the branch had been taken 

 from the tree, these cones were sent to the Harvard Arboretum that 

 the vitality of the seed might be tested. 



The following is the result: 



All the seeds yielded by the cones were planted on the 27th of May, 

 1879, those of each year in a separate pot. They all received the 

 same treatment. The final examination was made on the 13th De- 

 cember, 1879. 



1865 — 18 seeds from 3 cones were planted. None germinated. 

 1866 — No seed was obtained from the single cone of this year. 

 1867 — No cones received for this year. 

 1868 — 24 seeds from 2 cones were planted. None germinated. 



4 

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" " None " 



This experiment is unsatisfactory owing to the want of seeds of 1866 

 and 1867, and because those of 1873 had probably never been fully 

 developed. It is only interesting in view of the fact that it may pos- 

 sibly lead to this subject being more fully investigated. It is particu- 

 larly desirable to obtain and test the seeds from old serotinous cones 

 of such species as Pinus serotina, the Florida P. inops var. claiisa, 

 P. tuberculata, P. muricata, and P. insignis. There are always facili- 

 ties for making such experiments at the Arboretum when sufficient 

 material can be obtained. — C. S. Sargent, Brookline, Mass. 



Vegetation Under the Electric Light. —In the number of 

 iV^?/?//^ for March 11, appears the extract of an important paper by 

 Dr. C. W. Siemens presented to the Royal Society on March 4. The 

 question as to whether or not the dissociation of carbon dioxide and 

 water in the leaf cells of plants could be made to take place under ar- 

 tificial light as it does under sunlight, caused Dr. Siemens to under- 

 take the experiments described. The apparatus consisted of a verti- 

 cal Siemens' dynamo-machine making 1000 revolutions per minute, 

 and driven by an Otto gas engine of 3 horse-power ; furnished with a 

 lamp with carbon electrodes of 12 and 10 mm. diameter; producing 

 a light equal to 1,400 candles. In the first series of experiments the 

 lamp, with metallic reflector, was placed in the open air, two meters 

 above the glass of a sunk melon house. Pots of quick-growing 

 plants, such as mustard, carrots, beans, cucumbers, etc., were so 

 arranged that the light would fall on them at approximately the same 

 angle as that of the sun, provision being made for their protection 



