54 



HA R D WI CKE ' S S CIENCE - G SSIP. 



sorts of precautionary measures are necessary to en- 

 sure safety. First of all, the tuber is heart-shaped 

 like a fishing-float, not inversely heart-shaped like 

 the bulb of a bluebell, and the rootlets proceed 

 from the plumule and not from the solid base. 

 It has taken some time and much experimental 

 observation to discover the reason for this arrange- 

 ment, and indeed I am by no means sure that I have 

 rightly apprehended the truth, even now ; but I am 

 tempted to put down the reason as it appears to me, 



plant would be unarmed in the great struggle for 

 existence, for it cannot abide deep-planting. To 

 meet this peculiar requirement, how admirably is the 

 shape of the tuber adapted ! Before it is detached, 

 it is oval : after its detachment it -is heart-shaped : 

 which accords with the law of solid bodies moving 

 through liquids, whereby the larger and heavier part 

 is made to go first. To ascertain this, I planted 

 thirty-six tubers of Orchis mascula in a shallow box, on 

 August 1st, 1SS1, and a single tuber in a deep large 



Fig. 43. — A, Tubers of Orchis mascula (April) ; B, roots ; c, neck. 



for there is no help to be gained from the books. 

 The new tuber, being formed at the side of the old 

 tuber, is evidently not intended to occupy the same 

 space, but, on the contrary, it is purposely pushed 

 more deeply down into the soil where the springs of 

 life are not exhausted. Thus the plant makes a little 

 journey annually, the tubers in April being about two 

 inches below the surface, whereas in August they are 

 six inches deep. So far from this being a fortuitous 

 circumstance, it is one of those precautionary 

 measures already mentioned, without which the 



pot. The plants all flowered last spring, but with 

 this great difference : those in the box appeared 

 above ground in September, they kept their spotted 

 leaves through the winter, and were in flower by 

 March 20th ; whereas that one in the pot did not 

 appear above ground till February loth, and was 

 not out in flower till April 30th ; after which it died, 

 while the others survived. The case of the bluebell, 

 which has to meet different engagements, is exactly 

 the opposite : the bulb is inversely heart-shaped, the 

 roots proceed from the solid base, and the plant starts 



