OBSERVATIONS UPON THE PIIEN0:MENA OF PLANT-LIFE. 311 



rind of the squash. It was not feasible to remove the harness and substitute 

 for it a stouter one, on account of its being imbedded in the substance of the 

 squash, which grew up through the meshes of the harness, forming protuber- 

 ances an inch and a half high and overlying the iron bauds. When, on the 

 seventh of November, the harness was removed in order to take a plaster cast 

 of the squash, it was necessary to cut the straps with a cold-chisel, sometimes 

 into several pieces, and draw them out endways. 



The growing squash adapted itself to whatever space it could find as readily 

 as if it had been a mass of caoutchouc ; nor did it ever show the slightest ten- 

 dency to crack, except in the epidermis. This would often open in minute 

 seams, from which a turbid mucilaginous fluid exuded. In the morning, drops 

 of this would frequently bedew the protuberances like drops of perspiration. 

 In the sunshine these dried up and fell off as minute globules, resembling gum 

 Arabic. 



The lifting power was greatest after midnight, when the growth of the vine 

 and the exhalation from the foliage was least. 



The material out of which the squash was formed was elaborated in the 

 leaves during the day-time, and transferred through the vine to the stem. 

 Through this it was imbibed by the living, growing cells of the squash, which 

 were constantly multiplying by subdivision until their number was many bil- 

 lions, nothwithstanding the enormous pressure under which they were forced 

 to develop. This growth was possible only because life is a molecular force 

 and exerted its almost irresistible power over an immense surfixce of cell mem- 

 brane. 



Scarcely less astonishing than the mechanical force exhibited was the ability 

 of the tissues of the squash to resist chemical changes and the attacks of mould, 

 when the rind was injured by bruises or cuts. Whenever fresh-growing cells 

 were exposed to the action of the air, they immediately began to form a regu- 

 lar periderm of cork, precisely similar in appearance and structure to that 

 produced upon the cork-oak, the elm, and other trees. 



The form of the squash can hardly be described, but may be seen in the 

 drawings which show the upper and under sides. The weight was forty-seven 

 pounds and a quarter, and when opened the rind was found to be about three 

 inches thick and unusually hard and compact. The internal cavity corre- 

 sponded in general form to the exterior, but was very small, and nearly filled 

 with fibrous tissue and plump and apparently perfect seeds in about the normal 

 number. A squash of the same variety, grown in the field by Messrs. Russell 

 Brothers, in North Hadley, weighed one hundred and twenty-three pounds. 

 Its form was ovoid, but flattened as if by its own weight, and the cavity within 

 had a capacity of about sixteen quarts. 



PRESSURE OF SQUASH SAP. 



Two vines having been started together in our experimental bed, it was 

 decided to apjoly a mercurial gauge (such as will be described in another place) 

 to the neck of one cut off at the ground when the vine was about eight weeks 

 old and had a length of twelve feet. The result was quite surprising, greatly 

 surpassing anything heretofore recorded, so far as we are aware, concerning 

 the pressure exerted by the sap of an herbaceous plant, the maximum force 

 with which the root of the squash exuded the water absorbed by it being equal 

 to a column of water 48.51 feet in hight. The gauge was applied about noon, 

 August 27. At 2 P. M., August 28, the temperature of the pit being 8G^ 

 Fahrenheit, the pressure on the gauge equalled 31.70 feet of water. 



