^893. NOTES AND COMMENTS. 83 



word " Vitalism" has been born. Some time ago, we were all taught 

 to regard the human body as a machine. In digestion the processes 

 were regarded as simple chemical processes : in assimilation the in- 

 testines and the vessels were membranes obeying the laws of osmosis 

 and dialysis. Respiration was a simple interchange of gases under 

 conditions that could be paralleled with glass tubing and physical 

 apparatus. Now, all this is given up. The elements of the machine 

 are living cells, and the protoplasm of the living cells refuses to act 

 as a piece of apparatus, but remains isolated from, unaccountable to, 

 the laws of physics and chemistry. So, says the new physiology' 

 you must give up attempts at chemical and physical explanations ; 

 not only are they erroneous but fatally misleading. Protoplasm 

 must be studied as a thing of its own kind; its own facts taken 

 by themselves ; its own empirical laws sought after. 



Tropical Seeds in the Hebrides. 

 In the December number of the Annals of Botany (vol. vi., p. 369), 

 Mr. Hemsley gives an account of a drift-seed of the tropicll ipomJa 

 tuberosa which reached the Hebrides, probably from the West Indies, 

 by the agency of the Gulf Stream. Only one instance is recorded', 

 but from the fact of its having in Long Island a GaeHc name, signi-' 

 fying Mary's Bean, it would seem that its appearance on their shore 

 is not an extreme rarity. 



Physiological Action at a Distance. 



In the same number of the Ajtnals (p. 373), Professor Leo Errera, 

 •of Brussels, communicates an interesting note on the Cause of 

 Physiological Action at a Distance. This term was used by Elfving 

 to explain some phenomena of attraction and repulsion which did 

 not seem to belong to any of the known categories of geotropic, 

 hehotropic, hydrotropic, &c. He found that pieces of iron and, to a 

 less degree, of zinc or aluminium, as well as different organic sub- 

 stances, such as sealing wax or resin, attract the growing sporangium- 

 bearmg filaments of the well-known fungus, Pkycomyces niteus. All 

 other metals tried were inactive, and the filaments of Phycomyces itself 

 showed a mutual repulsion. 



From careful experiments, Professor Errera concludes that this 

 apparently mysterious action is merely a matter of hydrotropism • 

 hydrotropism (negative or positive) being the bending of a plant' 

 organ towards the point, not where it will find a minimum or 

 maximum of moisture, but where it will, within certain limits, lose 

 (by transpiration) the greatest or least amount of water. Knowing 

 that a surface which emits moisture repels the Phycomyces filaments 

 It seemed probable that moisture-absorbing substances would oroduce 

 the reverse effect, and attract them ; and as iron certainly absorbs 

 aqueous vapour when rusting, its action on the fungus filament might 



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