The Microscope. 315 



JjABOkatory Notes. — The usefulness of a simple and inexpen- 

 sive eye-2nece micrometer as a part of the outfit of each microscope 

 in the laboratory can scarcely be fully appreciated until one has tried 

 it. When the student has at hand at all times a means for making 

 accurate measurements, he will make many more records of measui'e- 

 ments than when he has to call upon the demonstrator for a special 

 eye-piece. A simple graded disk of glass which rests upon the 

 diaphragm of the eye-piece is sufficient. It is of course best to have 

 it in a second eye-piece, but in case the microscope has but one eye- 

 piece the disk can be easily removed when not needed. 



Cheap, and still efficient, culture cells for the growth of spores, 

 pollen, etc., may be made by the use of the little vulcanite rings now 

 sold by all opticians. A ring is fastened to a slide by means of gold 

 size; when dry and firm, a little oil is spread upon the ring, and upon 

 this the cover glass (bearing the hanging drops, in which are the 

 spores,) is carefully laid, care being taken to secure an air-tight 

 chamber. 



Very frequently a student wishes to preserve a specimen tem- 

 porarily, when he is obliged to leave the laboratory before completing 

 his work. This he can do with most specimens by simply applying 

 a drop of glycei'in at the side of the cover-glass in such a manner as 

 to effect a union between the water and the glycerin. The latter 

 will sloAvly run under the cover-glass and preserve the moisture of 

 the specimen often for many days.— C/ias. E. Bessey in Am. Natu- 

 ralist. 



Composition of Starch Grains. — Now comes A. Meyer and 

 denies in toto the Niigelian theory of the composition of the starch 

 grain, viz : that it consists of two substances, granulose and starch 

 cellulose intermixed. He concludes from his researches that in ordi- 

 nary starch, which turns blue with the iodine test, there is but one 

 substance, and that it is alike throughout, the layered appearance 

 being due to the varying porosity. Stiirch which turns red with the 

 iodine test has other materials mixed with the true starch-substance. 

 — Botanical Gazette. 



Raising Diatoms in the Laboratory — Under this title Prof. 

 Samuel Lockwood, Ph. D., communicates to the New York Micro- 

 scopical Society Journal his investigations of some sea-water which 

 had remained undisturbed for sixteen years in a demijohn in a dark 

 cellar. At the end of that time, requiring some water for a Sertu- 



