BIOLOGY. 291 



tainty. Therefore, this unnatural development of fruit, instead 

 of indicating an improvement of the trees, must be looked upon 

 as a premonitory symptom of disordered physical action, and of 

 premature death. 



If the bark and the cambium layer have been removed by gird- 

 ling, as seems to be .the case with the trees, the downward cir- 

 culatory connection on the outside between the upper and the 

 lower part is destroyed, and the upper part at least must die. If, 

 however, the cambium layer has not been' destroyed, and has 

 been so covered by wax and bandages as to prevent evaporation 

 and drying of the surface of the decorticated part, there is a 

 chance for some of them to live. It is true that some few cases 

 are recorded of trees which have lived several years after the 

 bark and cambium layer have been removed, but they are of very 

 doubtful authority. 



M. Ernest Faivre, a French physiologist, gives a statement of 

 his recent investigations on this subject, published in the "Gar- 

 dener's Chronicle," about two months ago, in which he says : "In 

 mulberry-trees, as in all trees deprived of latex, annular incisions 

 generally produce the following manifestations: 1. Formation of 

 a swelling, or tissue restorer, at the upper lip of the wound. 2. 

 Diametrical growth of the parts above the zone of bark taken oft'. 

 3. Hardening of the wood in that region. 4. Stationary condi- 

 tion of the parts below, if they are deprived of leaves and buds ; 

 or, if not, vigorous shoots from below the lower lip of wound. 

 5. More easy, more early, and more abundant flowering and 

 fructification. 6. Destruction, after a variable time, of all the 

 parts above the annulation." 



THE CIRCULATION OF THE CULEX. 



Mr. H. C. Perkins gives an interesting paper in the " Monthly 

 Microscopical Journal," for September. He says that, while 

 watching the circulation as seen through the lenses in the reflected 

 sunlight, if he moves the diaphragm from left to right, so as to 

 make the shadow enter upon the right of the field of view, a brisk 

 circulation (no matter how quiet it had been before) is instantly 

 witnessed, which appears to be changed in direction as the dia- 

 phragm is moved back again ; and that the direction of the circu- 

 lation can thus be changed at will by the interception of the 

 sunlight. This same result can also be witnessed by the passage 

 of clouds between the sun and mirror. The actual direction in 

 the plant is from the apex of the leaf in sunlight, and toward it 

 in the shade. This change in direction is so rapid when produced 

 by the shadow of fast-flitting clouds across the sun's disc that it 

 would seem that the change of temperature could hardly be felt 

 by the plant ; it certainly could not be by an ordinary thermom- 

 eter ; but a heated body, properly placed, will quicken the circu- 

 lation, as cold will retard it. If he mistakes not, we have here a 

 fine demonstration of the conversion of light into heat by its pas- 



