Proceedings of the Polytechnic Association. 1059 



should be sufficiently shallow to admit of no more than a single layer, 

 and at the same time deep enough to permit the grains to move about. 

 If pollen is mounted eoon after it has been discharged from the fresh 

 anthers, thefovUla is apt to condense on the covering glass, and the 

 slide soon becomes useless. The stamens taken from an unopened 

 flower-bud furnish the best and cleanest pollen, and these sliould be 

 selected in preference to those taken from the fully developed flower. 

 Canada balsam, glycerin, and other media are occasionally helpful in 

 making out structure ; thus the pores of campanula 7'otund[folia^ 

 2'>Jiyteuma liaUeri., and other allied species are made much more dis- 

 tinct when mounted in balsam. 



The Gulf Steeam. 

 The Hon. Charles P. Daly, President of the American Geographi- 

 cal and Statistical Society, in his annual address, after giving an 

 interesting summary of important geographical and scientific events 

 Avhich have occurred during the past year, alludes to the latest attempts 

 to find at the far north a passage from the Atlantic to the Pacific 

 ocean. He states that there have been about 113 expeditions from 

 the first under Sir Hugh Willonghby, in 1553, to the present year, 

 specially sent out either to find a northeast or northwest passage, or 

 to reach the pole, or to rescue previous expeditions, or obtain scientific 

 information, the details of which fill nearly 1,000 volumes. The 

 main portion of the address is devoted to a criticism of Capt. Silas 

 Bent's theory, viz. : That the gulf stream of the Atlantic and the 

 %varm Japanese current of the Pacific are each prolonged to the 

 vicinity of tlie pole ; where bethinks these currents unite, and dis- 

 charging their heat, produce an open polar sea. The currents are 

 tlie prime and only cause of the existence of this sea, and constitute 

 the only practicable avenues by which ships can reach it or the pole ; 

 or, to use his own language, the way to the pole is by following the 

 course of these currents, which are water thermometers, and may be 

 termed the theruiometric gateways to the pole. In consonance with 

 this theory, Capt. Bent assumes that the northerly branch of the gulf 

 stream extends around the coast of Norway, and runs from thence 

 eastward of Spitzbergen to the pole ; and that the Japanese current, 

 Ji-u?'o-iShvo, is prolonged through Behring straits in a northeastwardly 

 direction, until it encounters and mixes with the other in the vicinity 

 of the pole. There is a powerful current running in a northeasterly 

 direction through Bshring straits, known on the maps as the Kamt- 



