HARDWICKE'S SCIENCE-GOSSIP. 



55 



from a depth of seven or eight inches below the 

 surface. One is here naturally led to ask why, sup- 

 posing the above to be true, hasn't nature contrived 

 that the new tuber should be settled in its proper 

 place at once — wouldn't that have been easier ? 

 Undoubtedly it would, but the general law, by which 

 the descending axis of plants is made to seek depth 

 and darkness, couldn't be broken ; and so the above 

 plan is adopted. What a proof of Divine care ! 



The rootlets are formed during the second stage of 

 the tuber's existence, and 

 are made up of an outer 

 skin with loose interme- 

 diary cells between the 

 skin and the central fibre. 

 They have the appear- 

 ance of whipcord, but 

 they are brittle and sen- 

 sitive. The cells are like 

 tapioca ; their function 

 is to absorb mineral moisture from the 

 soil, to supply the plumule and the leaves. 

 I think this must be the reason of their 

 position,' for if the tuber supplied the leaves 

 with nutriment, then clearly the rootlets 

 would have to start from the base ; and, 

 as a proof of this, I found in April a fine 

 plant in flower, perfectly healthy and vigo- 

 rous, but with the old tuber entirely de- 

 voured by slugs, and the new one meagre 

 and aborted. As it is, the rootlets spread 

 upward, downward, and horizontally, either 

 drawing the tuber to the surface and help- 

 ing it to shoulder its way higher, or else 

 preventing it from descending any lower. 



The last thing to notice about the tuber 

 is its extraordinary scent, which resembles 

 the scent of carbolic acid, nitrate of silver, 

 or the reptile house at the Zoo. It is in- 

 creased by darkness and moisture. It 

 produces a chill shuddering sensation, if 

 inhaled for any length of time, accom- 

 panied by a feeling of headache and nausea. 

 Now, I am anxious to know if this peculiar 

 unsavoury reptilian odour is in any way a 

 protection to the orchis, and I should feel 

 greatly obliged to anyone who would en- 

 lighten me. Consider the life history of the plant. It 

 grows in meadows and hedges at a time of the year 

 when the weather is severe, and forage for small 

 animals very scarce. The gardening journals for the 

 spring of iSSl contained many notices of the ravages 

 made by mice among bulbous plants; but, although I 

 have found many tubers destroyed by slugs, I have not 

 as yet observed the marks of teeth on them. Why 

 don't mice gnaw the tubers of the common orchis ? 

 I will venture an explanation. Anything bitter is 

 rejected by men and animals as disturbing the bile : 

 the case of buttercups and toads will readily occur. 

 Cats and dogs turn from shrew-mice in disgust, but 



hedgehogs and snakes devour them. Can this odour 

 be intended to warn shrew-mice fof their natural 

 enemies ? If so, what a truly remarkable plant the 

 orchis is ! for there seems to be nothing but protective 

 precaution about it. The case of the bluebell does 

 not interfere, it will be noticed, with this explana- 

 tion, because the orchis is only required in sparing 

 abundance, as will be shown hereafter, and affords 

 no pollen ; whereas the bluebell is deeply planted and 

 supplies vast quantities of pollen. The cold clammy 



Fig. 44. — a, Root of Orchis mascula ; b, transverse section of root ; 

 c, longitudinal section of root. 



reptilian character of the orchis certainly deserves 

 greater attention on the part of botanists. 



The stem and leaves. The skin of the common 

 orchis is a scape, or a simple erect herbaceous hollow 

 cylinder, rising directly from the root and elevating 

 the flower,'but not the leaves. It dies as soon as the 

 seed is set, and when dry has a pungent snuffy odour. 

 Its cellular tissue is arranged in isolated bundles. 

 There is nothing extraordinary about the 'stem, 

 except the fact that breaking it prevents the new 

 tuber from flowering the following year. The Rev. 

 B. S. Maiden was kind enough to point this out, for 

 I was puzzled to know why some plants, with many 



