290 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



ACTION OF LIGHT ON THE TISSUES OF PLANTS. 



According to Botalin, notwithstanding the many experi- 

 ments that have been made in regard to the physiology of 

 vegetation, little or nothing has been determined as to the 

 action of light upon the tissues of plants. This gentleman 

 has, consequently, occupied himself in prosecuting inquiries 

 in relation to this subject. His memoir, lately published by 

 the Academy of Sciences of St. Petersburg, contains an ex- 

 haustive detail of observations and researches on this sub- 

 ject, but our space will permit us to give only a few of the 

 practical conclusions to which he came. Among these may 

 be mentioned the following : Direct sunlight or strong listfit 

 retards the subdivision of the chlorophyl parenchyma cells, 

 while diffused light favors such a division in the parenchyma 

 cells of the bark. Absence of light has the same retarding 

 effect as strong light. Light has no influence upon the divi- 

 sion of the epidermis cells. Strong light, as well as entire 

 darkness, retards the division of the cells of the parenchyma 

 of the bark. The absence of light produces a slight thicken- 

 ing of the parenchyma cells. Light exercises no influence 

 upon the thickening of the cells on the inside bark, and of 

 the wood. Mel. Biol. Acad. 8c. St. Petersburg, 1870,VIL, 269. 



CHANGING THE COLORS OF THE FLOWERS OF THE HY- 

 DRANGEA. 



Some of our readers may not be familiar with the readiness 

 with which the color of the flowers of the common garden 

 hydrangea can be altered artificially. If a sixth part of iron 

 filings be mixed with the earth in which the plant is grown, 

 it will frequently, although not always, change from its orig- 

 inal pink color to a light blue. A cutting, however, taken 

 from the plant thus changed, and grown without iron filings, 

 reverts* to its previous color. 6 A, 18/0, July 16, 81. 



GENERATION OF HEAT BY FUNGI. 



The statement of Dutrochet that a considerable amount 

 of heat is generated by fungi during the process of growth, 

 as well as of decomposition, has been substantiated by Mr. 

 Smith, who found it to be greater in the species of Boletus 

 fvneus than in any other plant excepting the Arum. In one 



