in iig. 7 is a common laboratory experiment and consists in pinning 

 a cork upon the upper and under sides of a leaf for a short time, 

 then removing the same and treating the leaves so as to bring out the 

 starch reaction. Photographic negatives are frequently substituted 

 for cork and the starch picture can be printed on the leaf. It is 

 worthy of note that even the cork, which is about three-fourths of an 

 inch in height in this experiment, cast a shadow sufficient to retard 

 starch formation. This shaded or lighter portion is shown more 

 prominently on the leaf than in the photograph. These experiments 

 fully agree with our observations made in various green-houses, 

 namely, that in cucumber plants grown in houses where the light 

 conditions are poor the photosynthetic activity is greatly retarded to 

 the detriment of the plant. These conditions, as has been already 

 stated, are brought about by double layers of glass or by unclean 

 lights of single glass. The matter of shade caused by heavy frames 

 is also a factor that comes now and then into play in obstructing 

 light, (See p. 7) and in the same manner do the shadows caused by 

 adjacent buildings give rise to immature plants. It is just these 

 conditions that retard carbon assimilation, and upon the extent of this 

 retardation will depend the growth of the plant, other conditions being 

 equal. The conditions to which we have referred are especially 

 applicable to growing cucumbers in our latitude between the first of 

 November and February ; after that the intense rays of light, or more 

 properly the conditions to which they give rise in a house, are fre- 

 quently objectionable, and recourse to shading is perfectly rational 

 after that time. The practical importance of matters pertaining "to 

 light and carbon assimilation in cucumber growing cannot be neg- 

 lected, if one wishes to secure the best results with his crop or the 

 best returns for his investment. 



Fertilization of Flowers'. 



Cucumbers are monoecious plants, i. e., the sexes are borne in sep- 

 arate flowers on the same plant. For this reason, when cucumbers 

 are grown in greenhouses it is necessary to resort to hand pollination-, 

 or to employ bees to carry the pollen from the staminate to the pistil- 

 late blossoms. Bees are generalh' abundant enough in summer to 

 accomplish fertilization of outdoor crops. It is staled, however, by 



