232 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



made on the Minot microtome. To prepare the material 

 for this purpose, small parts of the frond of which a sec- 

 tion was desired were taken from the Wilson's solution in 

 which they had been left for about six hours, or from the 

 formalin in which they had remained an indefinite time, and 

 placed in ten per cent, alcohol from which they were dia- 

 lyzed into 95 per cent, alcohol. The specimens remained in 

 95 per cent, alcohol for an indefinite time, but never less 

 than twenty-four hours. The parts of the frond were then 

 folded in small bundles of about one-fourth of an inch or 

 less square and one-eighth of an inch in thickness; after 

 which they were transferred for three hours to 100 per 

 cent, alcohol. From this they were placed in a mixture of 

 equal parts absolute alcohol and bergamot oil. In this they 

 remained two hours, as they did in the bergamot oil to 

 which they were transferred. From the bergamot oil they 

 were passed into 45^ paraffin, a mixture of equal parts of 

 45° and 54° paraffin, and 54° paraffin, being during that 

 time placed in a water-bath which was kept at a constant 

 temperature of 56° C. In each of these they remained 

 from two to three hours. 



After this they were imbedded in 54° paraffin and on 

 cooling were ready for cutting. In most cases good results 

 were obtained. 



This method was extremely useful in determining the 

 number of divisions in the antheridia, which in compara- 

 tively thick razor sections with pith was very difficult to do. 



Razor sections were usually stained with eosin, while 

 microtome sections were stained with acid fuchsin or with 

 safranin. Of the two, the latter gave the better results. 



In a single case, that of P. naiadnm, a double stain, 

 methyl-blue-safranin, was used with exceedingly gratifying 

 results. The slides were passed from xylol into absolute 

 alcohol, 95 per cent, alcohol, and a saturated alcoholic solu- 

 tion of safranin. Here they remained for about half an 

 hour, after which the slides were placed for five minutes in 

 95 per cent, alcohol to which some drops of method-blue, 

 enough to give the alcohol a deep blue tinge, had been 



