NOTES. 



287 



free from ice at that time. This immigra- 

 tion must have taken place during repeated 

 changes of climate. " After several thou- 

 sands of years with a severer climate that 

 favored the immigration and extension of 

 northern and eastern species, other thou- 

 sands of years followed with a milder cli- 

 mate. During this period fresh immigrants 

 came from the south and southwest, com- 

 pelling the older flora to retreat. In this 

 manner the climate must have changed sev- 

 eral times since the Glacial age, and the 

 distribution of the plants must have changed 

 in accordance therewith. The periods of 

 variation are reflected in the present flora, 

 and it is the former which have led to the 

 great gaps in the extension of coast as well 

 as inland plants. The sunny screes, the 

 slate districts, and the moist coast tracts, 

 are asylums where the different floras have 

 found refuge. In the intermediate parts 

 they have been dislodged by the new-comers. 

 But certain species, being indifferent to the 

 variations, extended constantly, at the ex- 

 pense of others, and this is the reason of 

 the Norwegian flora being so monotonous." 



Artificial Digestion. 0. Petersen, of St. 

 Petersburg, has made experiments to ascer- 

 tain the influence of certain medicines on 

 digestion. The problem he set himself to 

 determine was the time required to digest 

 from 20 to 40 grammes of dried albumen 

 by the aid of 450 centigrammes of a spe- 

 cially prepared artificial gastric fluid. Al- 

 cohol in the proportion of five per cent 

 did not hinder digestion, but the process 

 was retarded as the percentage rose, and 

 stopped at ten per cent of alcohol. Anti- 

 pyrin, in light doses, was without influence, 

 but in larger quantities slightly retarded the 

 action. One or two grammes of bromide or 

 iodide of potassium hindered the process a 

 little. The organic preparations of iron 

 scarcely affected the time required for the 

 digestion, while reduc d iron and the inor- 

 ganic salts slowed the action, as did also 

 magnesium and sodium sulphates, even in 

 moderate doses. A gramme-dose of chloral 

 hydrate had no slowing effect, though a 

 marked retardation occurred with a dose of 

 a gramme and a half. Chloride of sodium 

 did not retard digestion, even when em- 

 ployed in large doses. 



NOTES. 



A series of charts, showing the surface 

 temperatures of the Atlantic coast waters, 

 from Maine to Florida, is under preparation 

 by the United States Fish Commission, as- 

 sisted by the Lighthouse Board and Signal 

 Service. Observations, covering five years 

 in time, have thus far been made at twenty- 

 four lighthouse-stations. The temperatures 

 at the several stations are shown for each 

 year by ten-day means, and in such a man- 

 ner as to give the isothermal relations of 

 the stations. 



It is said, on the authority of " an Ameri- 

 can railway engineer," that low tempera- 

 tures do not decrease the strength of rails, 

 as is commonly supposed, although it is 

 true that accidents are more likely to occur 

 from broken rails in cold weather. This is 

 because, when the ground is frozen hard, it 

 loses its elasticity. Nevertheless, something 

 must yield when the train rune over the 

 road; it is the ground that yields in un- 

 frozen weather; but during a freeze the 

 ground will not yield, and the rail, as being 

 the weakest part of the structure, has to 

 suffer the consequences. 



Mr. Blanford, in his report on the " Ad- 

 ministration of the Meteorological Depart- 

 ment of India" for 1885-'86, describes the 

 steps which have been taken in the penin- 

 sula to discover to what extent forests influ- 

 ence the rainfall. A few observatories have 

 been established in the Ajmcre forests, and 

 the results so far have been to show slightly 

 but appreciably higher rainfall in the for- 

 ests than without. It is admitted that more 

 careful inquiry must be made before any defi- 

 nite conclusions can be drawn. Mr. Blan- 

 ford points out that M. Woeikoff, in a paper 

 on the subject with special reference to In- 

 dia, essentially supports the view, which he 

 himself regards as probable. 



The Paris Academy of Medicine has been 

 discussing the bad results of mental strain 

 on young persons. A particularly hard 

 bearing of the process was shown upon 

 French girls, twelve thousand of whom are 

 competing for diplomas entitling them to 

 two thousand appointments in government 

 schools. 



Professor Sargent, Director of the Ar- 

 nold Arboretum, of Harvard College, esti- 

 mates that five foreign trees are planted in 

 New England to one native. Yet, of all 

 foreign trees introduced into America, the 

 willow alone, he thinks, has qualities not 

 possessed in a greater degree by some na- 

 tive. The European oak, and the Scotch, 

 Austrian, and Corsican pines all die at about 

 the time when they should be at their prime, 

 and the Norway spruce, at a corresponding 

 age, is decrepit and unsightly. 



