264) General "Notices. 



A twig of Jasminum fruticans was divided from its tip down the middle, when 

 the segments instantly separated, and they remained separate when the twig 

 was held in an inverted position ; thus showing that the effect did not depend 

 on the segments bending outwards from their own weight. 



Nature and Cause of the Phenomena. — They must depend on physical elas- 

 ticity, or on that vital contractile power which is called irritability. No other 

 known principle suggests itself to which I can reasonably ascribe them. 



Facts ivhich oppose the ascribing the Divergence to Elasticity. — The woody 

 parts of trees, and even the rattan cane, which are certainly some of the most 

 elastic vegetable substances, never exhibit divergence on division. [The editor 

 of the Phil. Mag. here annotates that a botanical friend has suggested the 

 enquiry, whether Dr. Johnson has ever tried the effect of division on any plant 

 of the natural order T'hymelae'ae.] The stems of many plants, the common 

 teasel one, which in their recent and growing state are divergent on division, 

 lose this property when they become dead and dried, although they are 

 more elastic in the latter case than before. — Poisons destroy [Dr. Johnson 

 has found by numerous experiments] the power of divergence, which they would 

 not do if it were dependent on a mere physical cause, such as elasticity. 



Facts which led Dr. Johnson to conclude that a vital Property causes the 

 Divergence. — The divergence " is most active in those parts of plants which 

 exhibit other vital properties and functions in the greatest perfection. For 

 instance, while it does not exist in dead wood, and ceases as a plant loses its 

 moisture, it is found in stems, and flower stalks, and leaf stalks when in their 

 most vigorous and healthy state." Poisons are known to destroy vitality. 

 Dr. Johnson placed " a stem of bryony (i?rydnia dioica) in a solution of 

 arsenite of potash (made by boiling together in 1 oz. of water, 8 grs. of white 

 arsenic and 8 grs. of subcarbonate of potash). In two days it became so 

 flaccid that the head and tendrils hung downwards ; they were not discoloured, 

 and but little shriveled. The divergent power was completely destroyed. I 

 confined two stems of the red [coroUaed] dead nettle (iamium purpureum) in 

 an inverted jar filled with sulphuretted hydrogen. In two days one of the 

 stems was so perfectly flaccid as to be incapable of holding up its head. They 

 were not withered, and the blossoms only looked a little paler. Ever}' part 

 of the stems which was exposed to the influence of the gas had completely 

 lost its divergent power. 



Stimulants ivhich excite or increase the Power of Divergence. — Many poisons 

 whose ultimate effect is to destroy this power, do, at first, increase it. This 

 has occurred with laurelwater, dilute nitric acid, brandy, oil of turpentine, 

 hot water, and a mixture of ether with sal volatile. Cold water, also, so 

 augments the divergence of the segments of a divided stem, that they become 

 curled up in circles or spiral coils. Every one has seen an instance of this in 

 celery when dressed for table. More remarkable proofs of the effects of 

 stimulation were supplied in the following cases. Several pieces of the stems 

 of different plants were divided, and, when in a state of divergence, were im- 

 mersed in hot water ; the divergence was at first increased in all, but in a 

 few minutes the diverged portions entirely collapsed, and theii" divergence was 

 totally destroyed. In a young and vigorous peduncle of dandelion, which 

 curved to the left, several notches were cut in the concave side: the peduncle 

 instantly became erect; and, on cautiously applying a heated poker near the 

 entire side, the fibres in the latter appeared to be contracted, and the peduncle 

 now inclined to that side the opposite to that to which it inclined at first. — 

 J.D. 



In receiving and exchanging Seeds, a correspondent alleges that a good deal 

 of deception is sometimes practised by gardeners. It is alleged that the gar- 

 dener who possesses a choice variety of fruit or flower sometimes indulges in 

 " a secret pride to retain the sort to himself; " and if he is asked by a neigh- 

 bour for a plant or seed, instead of candidly refusing it, he gives something 

 else. This is, no doubt, very reprehensible conduct, and can only proceed 

 from a very short-sighted view of the duties which man owes to society, and 



