IOWA ACADEMY OF SCIENCES 211 



U. S. Department of Agriculture, where it has been car- 

 ried on especially with reference to fertilization and its 

 results'. Botanists have usually selected such material as 

 could be most easily worked up, e. g., such plants as many 

 of the Ranunculacese and Liliacese, plants which have 

 large pistils and large cells, and are easily oriented in 

 paraffine. The Leguminous plants have not been so gen- 

 erally worked with, because they are ordinarily more diffi- 

 cult to handle. 



The material used in the preparation of this paper was in 

 all cases collected in close proximity to the laboratory and 

 carried there before killing. Various killing mixtures were 

 employed, viz.: Aqueous solution of corrosive sublimate. 

 Distilled water, 100 parts, by w^eight. Sodium chloride, 6 

 parts. Acetic acid, 6 parts. Mercuric chloride, 3 parts. 

 One-third per cent, aqueous solution of platinic chloride. 

 Flemming's weaker solution : 



Chromic acid, one per cent , 25 vols. 

 Osmic acid, one per cent., 10 vols. 

 Acetic acid, one per cent., 10 vols. 

 Distilled water, 55 vols. 



Hermann's solution: 



Platinic chloride, one per cent., 15 vols. 

 Glacial acetic acid, two per cent , 15 vols. 

 Osmic acid, two per cent., 2 vols. 



After killing, the material was hardened in alcohol and 

 stored in 80 per cent, alcohol. It was imbedded in paraf- 

 fine and sectioned, 6-10 u, generally 6 u. 



The best results were obtained from material killed in 

 Flemming's. Good results were also obtained after platinic 

 chloride. Hermann's, although one of the best killing 

 reagents did not yield good results because the material 

 was not decolorized, thus rendering staining very difficult. 

 In imbedding, much difficulty was experienced in orient- 

 ing the specimens. In very young pistils no trouble of 

 this kind is met, but as they become older and the ovules 

 are developing rapidly, they crowd each other out of posi- 

 tion and drop in the cavity of the pistil, and the way they 



