THE MICROSCOPE, 183 
BOTANY. * 
Potten Moruer-Cetis.t—Byron D. Halsted says that pollen 
mother-cells in excellent condition for study may be found in the 
young anthers of Negundo aceroides, Moench. Sections may 
be obtained by cutting across the staminate flowers before they have 
attained half their full size. When the sections are not too thin, 
the thecze will be found made up of a single whorl or circle of 
mother-cells, many of which are pear-shaped, due to unequal 
pressure. The mother-cells in the center of the thece easily become 
detached, and may be found scattered through the liquid in which 
the sections are immersed. ‘These loose cells have a strong resem- 
blance to the loose asci of the Erysiphez (powdery mildews), and 
the fair pollen grains may be found in all stages of development. In 
the beginning there is only the slightest differentiation of the 
protoplasm into four indistinct masses. As they become more 
manifest, the arrangement of the four is found inconstant. Some- 
times they are placed with their large diameter parallel, like the 
four mitlets of a borrage fruit. In others, two are in the same 
plane, and the other two above or below and at right angles to the 
first pair. Azorubin is excellent in weak solution for bringing out 
the young grains more prominently. The pollen grains do not use 
up the thick mother-wall, and leave pits or cavities as they escape, 
as young seed in a wax-bean pod. 
MICROSCOPY. 
A New Mepivum ror Mounrine Srarcues anp Potiens.§-—Mr. A. 
P. Brown advocates the use of the following medium for starches, 
pollens and vegetable tissues : 
Selected gum arabic, 2 If. 
Glycerin. 
Distilled water, each, = 14. 
Thymol, gr. I. 
Put into a wide-mouth, well corked bottle, and place in a warm 
situation. The mixture should be occasionally stirred until a 
perfect solution is effected, which usually takes several days. When 
*Under this heading will be included all Abstracts relating to the various 
departments of Botany. 
+ Botanical Gazette, April, 1889. 
¢ Under this heading will be included descriptions of New Instruments, Micro- 
scopical Manipulations, Stains and Re-agents, Photomicrography, etc. 
§ American Journal of Pharmacy, April, 1889. 
