4 Lawson . — The Gametophytes , Archegonia , Fertilization , < 2 /^ 
Flemming’s strong solution. 
3. Chrom-Acetic mixture. 
4. Chromic Acid — 1 °/ o sol. 
5. Alcohol Acetic. 
Of these Flemming’s weak solution probably gave the best results 
although equally satisfactory fixation was generally obtained by the 
Chrom-Acetic and one per cent Chromic. The Alcohol Acetic solution 
proved to be a failure. 
The fixing fluids were always taken into the field and the material 
deposited in them immediately. In the very early stages of the ovules 
and also of the pollen no dissection was necessary. On account of the 
air present in them these structures had a tendency to float. This diffi- 
culty was, however, overcome by sinking the material in the fluid by 
means of cotton plugs. 
In the very early stages the entire ovules were removed and im- 
mediately killed without further dissection, but in all the later stages it 
was found necessary to remove the integument. This, however, was not 
resorted to until after the pollen-tube had penetrated the nucellus. To 
insure rapid fixation most of the dissections were made with the material 
immersed in the fluid. The ovules were removed one by one, placed in 
a watch-glass containing the fixing reagent and while in the fluid the in- 
tegument was immediately removed by means of a sharply pointed scalpel 
and forceps. With a little experience this may be accomplished very rapidly. 
The material was allowed to remain in the fixing fluid from ten to 
twenty-four hours and then washed in running water from four to six 
hours. Care was now taken in transferring the material to alcohol. For 
this purpose Schleicher and Schull’s diffusion shells were used. The 
shells were cut to the height of small beakers and the material placed 
in the bottom, and 95% alcohol placed in the beakers. Water was now 
poured in the shell in sufficient quantity to make the combined solutions 
about 7o°/ o alcohol. By placing the shell, containing the material and 
water, in the beaker containing the 95 °/ o alcohol, a gradual diffusion took 
place which was not sufficiently rapid to cause shrinkage. In two or 
three hours the material was transferred directly to 95 °/ o alcohol. I found 
the shells much more convenient than ordinary parchment paper. 
In preparation for imbedding the material was thoroughly dehydrated 
in absolute alcohol. Bergamot oil was used to precede the infiltration of 
paraffin. After dehydration the material was placed in a mixture of 
1 part absolute alcohol and 1 part bergamot oil ; then into pure bergamot 
oil ; then into a mixture of 1 part Bergamot oil and 1 part melted paraffin ; 
and finally into pure paraffin. 
Minot’s wheel microtome was employed for cutting and the sections 
varied from 2 //, to 8 /x in thickness according to the detail desired. 
