26 
ing, and demonstrate the peculiar sensitivity of the leaf to a series 
of irritations, rather than, as generally stated, to the first impulse. 
A record is given of the plants memory of impulses, and of its 
memory-duration under varying temperature. A second series of 
experiments show that closure is not altogether dependent upon 
irritation of the sensitive hairs, the outer as well as the inner sur- 
face of the leaf proving sensitive, but in a less degree. Structur- 
ally, the author has especially considered the irritable hairs, and 
the questions of inter-cellular passages, and of inter-cellular proto- 
plasmic connections. The origin of the contractile impulse is cen- 
tralized in the joint of the irritable hairs; here a first mechanical 
impulse coralizes the protoplasmic elements and arranges minute 
permeable areas in the contained sap,—a second stimulus begin- 
ning the process of squeezing out liquid into the permeable areas, 
and perhaps as well through the hair-joint cells. The discovery of 
transverse strie in the cell protoplasm suggests interesting 
structural relations with striped muscle. The author emphasizes, 
especially, the important functions of inter-cellular protoplasmic 
connection and the minor importance of cellulose extensibility. 
«* * The cellulose membranes are merely secondary strengthening 
sacs, that act much like the netting bags that surround rubber bel- 
lows. * * That contractility, alike in the animal and vegetable 
kingdoms is accomplished by migration of liquids through the 
protoplasmic substance, and that this is wholly determined by the 
molecular condition of the plotoplasm, irrespective of cell walls.” 
The utilization of starch during the process of contraction and se- 
cretion is also considered. Experiments in regard to secretion 
demonstrate that any protoplasmic irritation ( including electrical ) 
will cause the outpouring of the digestive juices, a process that be- 
comes as apparently continuous as if a nitrogenous body had 
been the cause of its excitation. The paper closes with some sug- 
gestive notes as to the evolution of the mechanism of Dionaea. 
BasHForD DEAN. 
Dionea—An Abnormal Development of the Inflorescence of. John 
W. Harshberger (Contr. Bot. Lab. Univ. Penn. i. 46, illus- 
trated. 
Distribution of the Flora of the Cape Region of Baja California. 
T. S. Brandegee (Zoe, iii. 223-231). 
