296 THE AMERICAN NATURALIST [Vol. XLVII 



The mutilation experiments all proved to be valueless 

 in the production of fertile seed ; nevertheless, they were 

 interesting, since they were the only methods, except 

 where actual crosses were made and where chloroform 

 gas was used, which caused any seed development. 



(See Table II — Mutilation Experiments.) 



Effects of Fumigation 

 Several species, the names of which are listed in Table 

 III, were exposed before the plants had reached the flow- 

 ering stage to gases given off by acetone, carbon tetra- 

 chloride, chloroform, ether, ethyl acetate, ethyl bromide, 

 ethyl chloride, ethyl iodide, and formaldehyde. As in 

 the previous experiments, the buds were emasculated 

 and bagged. The object of this experiment, as of the one 

 on mutilation of the plants, was to endeavor to upset the 

 normal development of the floral organs in such a way as 

 to cause the production of seed without the aid of fertili- 

 zation. 



The methods used in conducting this experiment were 

 simple. Plants, growing in six-inch pots, were fumigated 

 approximately one seventh of a cubic foot when drawn 

 in at the top. The bags were closed either around the 

 stems which had been previously surrounded with cotton 

 batting or about the top of the pots, the method of treat- 

 ment depending on the height of the plants. When 

 everything was in readiness for fumigation, the gas was 

 set free by the opening of the vial which was glued to the 

 interior of the bag. Though the seams and the bottoms 

 of the bags were sealed by melted paraffine, the retention 

 of all the gas was not expected. A sufficient quantity 

 was present, however, when acetone and formaldehyde 

 were used, for the foliage of the plants, treated with these 

 gases, to become noticeably injured. 



