DiotuBa Muscipula, Ellis. 39 



minute needle-like crystals almost more quickly than the eye 

 could trace. 



On surface view each gland cell in the resting state, or just 

 previous to secretion, shows one large vacuole of a reddish 

 color, or more rarely several small ones, surrounded by finely 

 granular protoplasm. As secretion proceeds a clear refractive 

 viscid globule pushes or oozes out from the protoplasm into 

 the purple vacuole, and at times divides it up. It presses 

 against the free wall face and gradually oozes out as a sur- 

 face excretion. The amount and continuity of the secretion 

 depend largely on root absorption, as it may cease soon after 

 first appearance if the soil becomes dry, or if reduced in 

 amount on this account it can be again increased by watering. 



As secretion proceeds the starch grains that are abundant 

 during the resting stage in the mesophyll cells seem to 

 change into a yellowish oil that dissolves readily in ether. 

 This travels along the bast cells or related elements of the 

 phloem, and is distributed radially from these. It is possible 

 that this oil may be so acted on that it may become the 

 source of the excreted formic acid already spoken of. 



IV. Leaf-opening. 

 We do not attempt at present to discuss the changes sub- 

 sequent to secretion, and the absorption of food materials that 

 have been digested by the secretion. In from ten to fifteen 

 days after closure the leaf re-expands, but remains rather 

 torpid for several days after doing so. A remarkable pecu- 

 liarity, however, has been observed in leaves that are just 

 opening after artificial stimulation, or after secretion and 

 digestion. When the leaf is a healthy one, and has not been 

 greatly exhausted by repeated acts of digestion, if one or two 

 of the marginal bristles on each leaf-half are firmly caught by 

 forceps, the halves very gently and steadily pulled asunder 

 and held in this position for one to two minutes, it will then 

 be found that the leaf remains in the expanded state and can 

 contract on stimulus. Thus, a leaf which had been mechani- 

 cally irritated was slowly opening fourteen hours after, and 

 when expanded was thrice irritated when it slowly closed. 



