2206 



Journal of Applied Microscopy 



course in physiology, botany or general biology. For these schools, and 

 it is to be hoped that their number will be constantly increasing, it will 

 be desirable to equip a room where this work can be advantageously 

 done. The size of the room will depend upon the number of students 

 to be accommodated at any one time. Professor Minot, in discussing 

 the unit laboratory plan, has recommended 17j^ square feet per student. 

 The room should be well lighted and should face north or east if possi- 

 ble. The tables can be of any convenient size or form. Where a number of 

 students are to be accommodated at a single window, the truncated form is 

 very satisfactory. Plate glass resting on a rubber mat is perhaps the ideal top, but 

 can rarely be afforded. The next best is a wood top, either a soft or hard wood, 

 stained with anilin black. (See Journal of Applied Microscopy, Vol. I, p. 145.) 

 This top will withstand the action of chemicals, even strong sulphuric acid for a 

 short time, wears many years, and can be applied to an old as well as a new top 

 after the old finish has been planed off. The room should be supplied with 

 water and have sewerage connections and, if possible, be supplied with gas. 



Sterilizers- 



I 



Fig. 1. — Simple hot air steri- 

 lizer made from a tin cracker 

 box. A, Circular opening 

 in side of box. a Copper 

 plate on short legs, b Per- 

 forated iron grate. 



APPARATUS. 



Two kinds of sterilizers will be necessary, one in which hot air 

 is used and which can be heated very hot. This is 

 called a hot air sterilizer or oven. Such a sterilizer 

 may be purchased, adapted to the needs of any labora- 

 tory, or one can be improvised. The oven in a kitchen 

 stove may be made to serve. A gas or gasolene stove 

 may be used in the laboratory. Or simply the oven 

 of such a stove may be rigged on an iron support and 

 heated by a Bunsen burner or, where gas is not avail- 

 able, a Primus or similar kerosene or gasolene lamp 

 may be used. A more simple form may be made 

 from a tin cracker box which has had a circular hole 

 cut in one side and then a copper plate fitted over 

 this inside on short legs, which is of the same shape 

 but slightly smaller than the side of the box. The 

 flame plays directly against this copper bottom. A 



grate should be placed about an inch above this 

 plate. It may be made of perforated iron (Fig. 

 1). The whole box should be covered with as- 

 bestos and may be heated with a Bunsen burner 

 or a Primus lamp. In this form of sterilizer will 

 be heated glass and metal apparatus, but for 

 culture media especially a steam sterilizer will be 

 necessary. This can be purchased, and the form 

 most widely used is the Arnold steam sterilizer. 

 A very simple yet efficient form, however, may 

 be made with a covered pail. The pail is per- 

 haps best made of galvanized iron, but a tin one 



_-_ V 



Fig. 2. — Simple steam sterilizer 

 consisting of a galvanized iron 

 pail with a cover a and a false 

 bottom b. 



