180 Wisconsin State Hoeticultueae Society. 



'the variety or species show much greater variation in this respect. 

 I am more than ever convinced that we may measure the enduring 

 powers of a given species by the rule given above: The size of 

 its capillary cells and the toughness of its fibre. 



Water in open space congeals at 32 deg., but in fine capillary 

 tubes it has been lowered to 4 deg. below zero, without solidifica- 

 tion. The condensed juices of a tree properly ripened for winter 

 are rich in mineral elements, and do not congeal at even a much 

 lower temperature; the exact point we do not know, but approxi- 

 mately at 5 to 10 deg. lower than pure water in similar circum- 

 stances. So we find: first, that the smaller the cells and the more 

 condensed the sap in them, the less strain upon the woody struct- 

 ure or the cell walls; and second, that the more woody the 

 fibre and the tougher it is, the less the liability to be injured by the 

 extreme changes of winter. 



M. DeCandolle gives the following as the law of temperature 

 with respect to its influence upon vegetation: 



" 1. All other things being equal, the power of each plant, and 

 of each part of a plant, to resist extremes of temperature, is in the 

 inverse ratio of the quality of water they contain. 



** 2. The power of plants to resist extremes of temperature is 

 directly in proportion to the viscidity of their fluids. 



" 3. The power of plants to resist cold is in the reverse ratio of 

 the rapidity with which their fluids circulate. 



"4. The liability of the fluids contained in plants to freeze, is 

 greater in proportion to the size of the cells. 



" 5. The power of plants to resist extremes of temperature is in 

 direct proportion to the quantity of confined air which the struct- 

 ure of their organs give them the means of retaining in the more 

 delicate plants. 



" G. The power of plants to resist extremes of temperature is in 

 direct proportion to the capability which the roots possess of 

 absorbing sap less exposed to the external influence of the atmos- 

 phere and the sun." . 



We are thus confirmed in our observations, and believe this to be 

 the basis for important rules of observation and judgment of the 

 endurance of a given variety of a species, as well as the law of 

 growth to •secure the highest condition of hardiness of the indi- 

 viduals of that variety. We have another phase of organic life in 



