ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 191 



soil gave a very dark-green leaf, while that in the sand was of a sickly 

 yellowish-green. 



The changes in histological structure may be summed up as follows. 

 A decrease in the transpiring surface and in the relative size of the 

 woody tissue of the root in a change from the loam to the sand. A 

 larger number of crystals for the clay soil than for the other two. A 

 greater wood-development in the loam. Variations in the number of 

 stomata were specific and not general. In some cases the loam had the 

 highest average, in others the clay, but in most cases the sand. In five 

 cases out of the six, the loam gave the thickest leaves ; in the case of 

 carnation the clay gave the greatest average. This increase in thickness 

 was caused by a general increase in thickness of all the tissues. Plants 

 crrowins: in the loam had the smallest number of trichomes. 



Variation in Carbohydrate Reserves in Stem and Root of Woody 

 Plants.* — Leclerc du Sablon has investigated the variation in the 

 amount of sugars and starch in the course of the year in certain trees. 

 He finds that the amounts reach the minimum in the spring, when 

 reserve material is being used up by rapid vegetation, and attain a 

 maximum in autumn at the end of the vegetative period. It is inter- 

 esting to note that during winter when growth is apparently at a stand- 

 still, the reserves diminish slightly. This may be due in part to their 

 change into substances which are not transformable into glucose under 

 the conditions of the experiment. Generally speaking, the root contains 

 more reserve-stuff than the stem. The experiments were made with 

 the chestnut, the pear, the peach, and the willow. 



Irritability. 



Functional Inertia of Plant-Protoplasm.f — R. A. Robertson re- 

 views a number of phenomena which illustrate the fact that plant-proto- 

 plasm, like animal protoplasm, possesses functional inertia. The latent 

 period and period of after-effect, which respectively precede the response 

 to a stimulus and persist after its withdrawal, are examples. As a wheel 

 in virtue of its inertia of motion continues to rotate for a time after 

 the driving gear is slipped, so isolated organs or their parts may for a 

 time manifest functional activity. Thus isolated chloroplasts continue 

 to assimilate, and the nuclei of staminal hairs of Tradescantia carry on 

 karyokinetic division after death of the protoplasm. In the acquire- 

 ment of new characters by living matter it is suggested that functional 

 inertia is a factor of importance. 



Movement of Perianth Leaves of Tulip and Crocus.J — A. Burger- 

 stein finds when flowers of crocus and tulip are exposed to a relatively 

 high and constant temperature, that the opening movement of the 

 perianth leaves proceeds for a short time with increased and then with 

 diminished speed, thereby confirming previous observations by Jost. 

 In opposition to Pfeffer, who explained such movements by unequal 



* Comptes Kendus, cxxxv. (1902) pp. 866-8. 

 t Proc. Eoy. Soc. Edinb., xxiv. (1902) pp. 200-4. 



j Jahresb. d. k. k. Erzherz. Rainer-Gymnasiums, Wien, 1902. See also Bot. 

 Centralbl., xc. (1902) p. 665. 



