CYTOGENETIC ANALYSIS 505 



growth. The long cover glass facilitates preparation of chromosomes. Properly squashed 

 metaphases generally appear along the long edge of the final slide preparation. 



1. Tightly stoppered type (not for C0 2 incubator) 



a. No. 14-1951 short length tissue culture tube, Leighton type. Bellco Glass, Inc. 

 Vineland, New Jersey. 



b. No. 14-1922 rubber stopper, silicone rubber, non-toxic. Size No. 0. Bellco 

 Glass, Inc., Vineland, New Jersey. (Silicone stoppers are manufactured by the West 

 Company, Phoenixville, Pennsylvania. Minimal order $10.00 for about 100 pieces.) 



2. Dual model for both conventional and C0 2 incubation 



May be used in the conventional manner by turning the rubber-lined bakelite cap 

 tightly or may be employed principally in conjunction with a C0 2 atmosphere with a 

 loosened cap. Autoclaving and assembly is simplified, as compared to steps necessary for 

 preparing the above type that requires a rubber stopper. The field is readily viewed with 

 either a conventional or inverted microscope. Shortened, slightly upturned neck facilitates 

 removal of the cover glass with conventional forceps, and prevents spillage of medium. 



Bonus Laboratory Products, P.O. Box 66, North Andover, Massachusetts. 



Gold Seal cover glass, thinness, is cut to any desired measurement for use in both types 

 of tubes (local supply house). 



Incubators 



An incubator design which provides excellent control of the temperature and has 

 adequate inlets and an effective seal to retain the proper level and distribution of the 

 desired mixtures of gases is most essential. In this laboratory, an efficient incubator design 

 has been found in the model 410 design by Labline, Inc. Other laboratories have had 

 excellent results with other designs and, therefore, the following refers to our present ex- 

 perience and serves purely as a guide to those who are contemplating similar needs, and is 

 not necessarily an endorsement of the product. 



This model incubator has been found to be satisfactory, provided the speed of the built- 

 in blower is reduced by setting the powerstat (at 60-70). These features are presently 

 being incorporated in the latest assemblies at the factory. The design provides for the 

 maximum utilization of space. Shelves are so placed as to permit use of flasks of multiple 

 sizes. In our laboratory, moisture is provided by means of setting a stainless steel pan 1-2 

 inches deep filled with water under the bottom shelf. In addition, the mixed gases (air 

 and C0 2 ) are passed through a fritted glass tube (Corning Glass 39533) placed in a 1,000-ml. 

 flask filled with water that is replenished directly from the faucet by means of a hose connec- 

 tion. This assembly eliminates the need for opening the top of the moisturizing unit each 

 time it becomes necessary to fill it. 



Model No. 210 C0 2 Cloning Incubator by Labline, Inc., is a smaller version of the 

 one described above. The model 410 is recommended as first choice because of its excellent 

 capacity. The smaller model 210 is useful whenever there is absolute need to refrain from 

 disturbing the environment, particularly after ultraviolet exposures and the like. The unit 

 has excellent temperature control and moisture must be provided by a similar assembly 

 described above. A small electric heating unit placed under the evaporating flask and 

 heated to 38-40° C. is very helpful in assuring ample moisture to the cabinet. 



An extra set of flow gauges and reducing valves needed for the proportioning of carbonic 

 gas and air to the incubator will help to offset accidental losses, when similar items in use 

 happen to become damaged or hampered by debris collecting along the lines. The present 

 model 410 in operation at this laboratory has the following C0 2 service settings : a Matheson, 

 low-pressure, pancake regulator no. 70 is set to deliver 6 lbs. of pressure which, in turn, is 

 reduced still further by means of a Hoke 992 flow gauge to read 1.0 liters per minute. 

 The C0 2 is regulated by means of a Hoke Phoenix 902 C reducing valve to read 6 lbs. The 

 needle valve is set to deliver a reading ofO. 15 liters per minute on a Hoke bantam 994 flow 



