12 



Methods in Plant Histology 



A bath which, if carefully watched, gives the very best results 

 can be made by any tinner, and is very inexpensive. The figure 

 on p. 14 shows the form and dimensions (Fig. 10). It is made 

 of copper 2 or 3 mm. in thickness. Several triangular pieces may be 

 cut from a single plate of copper. Brass may be used instead. The 

 three legs should be screwed into the triangular plate. There should 

 be two boxes to contain the paraffin. They should be about 10 cm. 

 long, 2 cm. wide, and 2 cm. high, and should have loosely fitting 



FIG. 8. Land's electrical constant apparatus, showing diagram of the automatic 

 switch, as described in the Botanical Gazette, November, 1911. 



covers. The long box makes it possible to have melted paraffin at 

 one end and paraffin just below the melting-point at the other end. 

 By careful watching this bath will give as good results as the most 

 expensive bath with its elaborate thermostat. 



With the disappearance of the glycerin method, the turntable is 

 disappearing from the botanical laboratory; but some objects, like 

 Nemalion and moss protonema, are still mounted in glycerin, and 

 so one still finds occasional use for this once necessary apparatus. A 

 serviceable form is shown in Fig. 11 (p. 14). The more expensive 

 turntables with devices for automatic centering present no practical 

 advantages and the centering devices are often in the way. 



