106 THE MICROSCOPE. July 
especially those which have floating leaves. A slice across 
the stem of a water lilly will show the air spaces. 
Q. 255.—What ts the function of steve tubes? J. LN. 
Sieve tubes or sieve cells are a part of the fibro-vascular 
system of plants. The young growing sieve cells are 
lined with protoplasm (cell material) and contain a watery 
liquid. They are concerned in the nourishment and growth 
of the plant. They are very delicate structures and not 
easily seen when unstained. 
Q. 256.—What is Gorgonia? Ts it seaweed ? 
Gorgonia are marine polyps growing in colonies they 
form fantastic, branched, or fan-shaped structures resem- 
bling sea-weed but are composed of a delicate horn-like 
material. They are of animal not of vegetable growth. 
Q. 257.— What ts the address of Dr. Joseph Collins? E. £. 
8%, ; 
The author of the paper in the Microscope for March, 
1892, regarding Edinger’s Drawing Apparatus was proba- 
bly Dr. Collins, of 135 Lexington avenue, New York City. 
He can surely be reached through Meyrowitz Brothers, 
Opticians, 295 Fourth avenue. 
PRACTICAL SUGGEST Fonte: 
By L. A. WILLSON, 
Revival of Rotifers.—Many microscopic animals endure 
drying and resume active life on the application of a drop 
of water. On a piece of bark, which had long been ina 
cabinet was seena liver moss, Frullania. ‘The leaves of 
this plant are complicate bilobed; the under-lobe is a hel- 
met shaped bag. Placing the Frullania in a drop of water 
on a slide and covering it, I was delighted to see three of 
these under-lobe bags. In one of these were two rotifers 
(yulgaris) and in each of the others were only one. ‘The 
water revived and rendered them very active. They 
spread their wheels and revolved them vigorously. 
