233 



land, falling only at Greenwich as low as 28° Fahrenheit. This severe 

 frost was followed in England by a period of exceptionally mild, 

 weather of probably unprecedented length. For ninety-seven days, 

 from December 13 to March 18, Mr. Glaisher's tables show that the 

 temperature was above the average on eighty -nine, aud below the aver- 

 age on only eight days, the mean excess for the wliole period being 5° 1 

 Fahrenheit. During the whole of this period of more than three months 

 the thermometer fell below the freezing poiut on four nights only, Feb- 

 ruary being entirely free from frost. The wannest period was from 

 March 1 to 8, when the maximum temperature ranged each day from 

 570 1' to GOO §/. 



On March 19, the temperature again fell below the mean, and continued 

 so for nine days, till the 27th, accompanied in Loudon and the neighbor- 

 hood by heavy falls of snow. The minimum temperature for March was, 

 on the 21st, 2(JO 2', being the lowest recorded since December 9. There 

 were nine frosty nights in March, against two iu the whole of the two 

 preceding mouths. For the week ending March 26, the mean temperature 

 was 31° Fahrenheit, or 10° lower than the mean for the week ending 

 March 7. The severe frost of March 21, following such a long period of 

 mild weather, has done an immense amount of damage to the fruit crops, 

 the pears and cherries having suffered more severely. It is remarkable 

 that, although the flowers were killed in the bud, the center being turned 

 perfectly black, they opened as if untouched, and presented a mass of 

 bloom looking to the eye entirely uninjured. On the early vegetable 

 the effects were no less disastrous. In the island of Jersey alone, whence 

 large supplies are usually obtained for the Loudon market, the damage 

 to the potato crop is estimated at many thousands of pounds. 



Influence op variously colored light on vegetation. — As 

 the result of a series of experiments upon the influence of variously col- 

 ored light upon vegetation. Dr. Bert has arrived at the following con- 

 clusions: 1. That green light is almost as fatal to vegetation as dark- 

 ness. 2. That red light is very detrimental to plants, though in a less 

 degree than green light. 3. That though yellow light is far less 

 detrimental than the preceding, it is more injurious than blue 

 light. 4. That all the colors taken singly are injurious to plants, and 

 that their union in the proportion to form white light is necessary for 

 healthy growth. 



The author has examined the transmitted light from the leaves of 

 rarious plants, and finds that there is a slight difference in the rays 

 which different leaves absorb and utilize 5 and this, he believes, ex- 

 plains the fact that certain plants flourish in the shade of trees, while 

 others wOl scarcely exist; in the former case it is supposed that the rays 

 required by the plant are not absorbed hy the leaves of the trees, but 

 in the latter they are. 



Physiology of Grafting. — Mr, Goeppert, in Silesia, gives results 

 of some observations in reference to tree-grafting, substantially as fol- 

 lows : Upon the vertical surface of the stock a tissue of parenchyma is 

 developed, proceeding from the medullary rays, which enters into inti- 

 mate connection with that of the scion. At the same time the cambium 

 of the scion unites perfectly, with that of the stock. The place of this 

 union remains visible, and is named by Mr. Goeppert the line of de- 

 markation. All development above this line belongs to the scion, all 

 below to the stock. The stock, entirely deprived of leaves, furnishes, 

 as it were, the crude sap to the scion, which by its organs of vegetation 

 assimilates it. But as §oon as the descending sap has passed the line 



