828 RECORD OF CURRENT RESEARCHES RELATING TO 



side, it assumes a direction of growth at riglit angles to the liglit, so 

 long as tlie illumination is of a certain intensity. If, other conditions 

 remaining the same, the distance of the plant from the source of light 

 is increased, an intensity is sooner or later attained at which the 

 filament alters its direction of growth, and becomes positively 

 heliotropic ; it grows more or less exactly towards the light. If the 

 earlier condition is restored, the plant assumes again its previous 

 direction. This is true both of positively heliotropic filaments and of 

 those which grow at right angles to the direction of the light. The 

 phenomena different from this exhibited by a plant of Vaucheria 

 rooting in the ground are no doubt due to similar causes ; but the 

 conditions have not been sufiiciently investigated. 



Case of Apparent Insectivorism.* — Professor Baillon, at a 

 recent meeting of the Linnean Society of Paris, read the following 

 notes : — 



Peperomia arifolia Miq., of which the variety arcjyreia is culti- 

 vated in so many greenhouses, has the leaves more or less deeply 

 peltate. I have seen stalks on which the peltation on certain leaves 

 was so exaggerated as to show on a cross-section a depth of nearly 

 4 cm. When the concave stalks take a suitable direction, water, 

 principally that from sprinkling, would accumulate and rest in these 

 receptacles, so well prepared to preserve it. Many small insects 

 would fall into the water and be drowned. Last year, when the 

 season v/as warm, and when the windows of the house w^ere often 

 open, the number of insects was very considerable, and these, soaking 

 in the water, gradually fell into decay, and it was remarkable that 

 there was during this not the least sign of any putrescent odour. 

 Those who believe in the doctrine of insect-eating plants may 

 perhaps in this be led to find an argument favourable to such theories. 

 They will add that the variety of colours so strikingly seen in these 

 leaves constitutes the agent of attraction for the insects to come and 

 be devoured. 



Three reflections, each of a different sort, here present them- 

 selves : — 1. Is it not remarkable that the exaggerated peltation of these 

 leaves is in this case accompanied by an apparent insectivorism, and 

 that the leaves of the plants known up to this time by botanists as 

 carnivorous, owe their sac-like or horn-like forms only to an excessive 

 peltation of their limb, as was demonstrated in the evolution of the 

 leaves in Sarracenia ? f 2. How can it be considered as a proof of 

 insectivorism, that plants like TJtricidaria grow better in a fluid 

 containing albuminoid compounds, when other plants grow equally 

 favourably in the same kind of fluid, which latter are never for a 

 moment thought to be carnivorous ? 3. How do the chief priests 

 of our science reconcile the two ideas, that the surface of the leaves 

 of plants is unable to absorb pure water in contact with them, and 

 that the same surface daily absorbs water charged with albuminoid 

 substances and the like ? 



* 'Nature,' xxii. (1880) p. 277. t ' Comptes Eendus,' Ixxi. p. 630. 



