15 



30. Chemotaxis. This term designates that directive force 



discovered by Pfeffer which controls the movements of 

 many organisms. Thus are the pollen tubes attracted 

 through the tissues of the stigma to the ovules, the sperma- 

 tozoids to the archegonia. In the illustration given the 

 bacteria are seen crowding into the tubes, attracted by 

 the KNO3. 



31. Microscopical Studies. 



a. Embryo sac of Liliufti rubrum. (Hermann's Platino- 

 aceto Osmic mixture and Strasburger's iodine green- 

 fuchsine method.) 



b. Pollen formation in Azalea viscosa. (Kernschwarz- 

 Victoria blue.) 



c. Abortive ovules of Musa (the banana). The sections 

 show the seed-coats and the nucleus perfectly formed, 

 although seeds are never matured. 



d. Longitudinal section of ovary of Onagi'a biennis^ show- 

 ing crystal-bearing sacs filled with mucilage and centrally 

 placed bundles of crystals (raphides). 



e. Transverse section of the last, showing the distribution 

 of the sacs. 



Nos. 29, 30 and 31 exhibited by Dr. Carlton C. Curtis. 



32. Microscopic Preparations and Drawings, illustrating 



the plate of cells by which the ordinary deciduous leaf 

 petiole is separated from the stem. Exhibited by Ada 

 Watterson, Barnard College. 



33. Microscopic Preparations and Drawings, illustrating 



one phase of Symbiosis ; Nostoc colonies in the thallus of 

 Blasia. Exhibited by Louise B. Dunn, Barnard College. 



34. Microscopic Slides, Powders, Leaves, Roots and Her- 



barium Specimens, illustrating some of the officinal 

 drugs and their adulterants.* Exhibited by Dr. Albert 

 Schneider. 



* Nos. 34, 35 and 36 were undertaken in the interest of the Research 

 Committee C (investigating powdered drugs) of the Revision Committee 

 of the United States Pharmacopoeia, to discover characters by which each 

 can be identified in a powdered condition. 



