Reactions and Products in Interspecific Crosses 151 



the location. The agony of origin, of initial stages, and struggle for place is not 

 seen; the type is produced or not as the result of a specific reaction, and at the 

 close of the reaction is completed as far as that reaction is concerned. In setting, 

 operation, and result the series is purely mechanistic and devoid of the uncer- 

 tainties of time-elements and time for fixation needed to produce stability of 

 type. 



In the instance here presented a precise reaction is produced that in about 

 1 per cent of observed instances results in a specific stable combination — that 

 from the start is physiologically isolated, and in all observed respects the 

 equivalent of a natural species and fully able to survive in nature. It arose only 

 in experiment. Thus far I have not been able to obtain it in experiment in 

 nature, but my attempts are not thorough nor extensive in this effort. I am 

 convinced, however, that the type of reaction seen shows clearly that the 

 realization of an operation of this sort in nature would at once produce a com- 

 bination which, if found in any habitat and of unknown origin, would pose in 

 faunistic lists as a species or other taxonomic element. There is no reason why 

 operations of this sort should not be of frequent occurrence in nature, and I have 

 no doubt that if we really knew what goes on we would be astounded at the 

 diversity of the trials of this sort that are by chance made in each season of 

 developmental activity. 



I know that the type that arose was stable from the experiences in the labora- 

 tory and inability to break it up, and its ability to survive was tested at a loca- 

 tion created for it at Tepextempa, Vera Cruz, Mexico, where it was placed ia 

 tropical savannah conditions in 1908 and without effort passed through four 

 generations in 1908 and 1909, being exterminated in the winter of 1910 by the 

 clearing of the fields for the planting of cane. It was introduced into the deserts 

 at Tucson in 1909 and thrived through two generations in that year, but was 

 killed in the winter of 1909-10 by defects in cage construction which prevented 

 them from penetrating deep enough into the earth to escape the desiccation of 

 the winter months. The entire population was found dead in the spring of 1910 

 along the wire bottom of the cage. The type could not be tested in nature in 

 any of the northern regions and could not be turned loose in nature, because 

 the food it could eat could not grow and survive the northern winter. I tried 

 it on potato at Chicago in inclosed spaces, and it was completely extermi- 

 nated, never even making a start at reproduction. It has the capacities, limita- 

 tion, and characters of natural species — and the experience is suggestive of a 

 method of origin of groups in nature that may prove to be of wide occurrence 

 and productive of much diversity in natural forms. 



It is suggestive that the observations show the origin of a group and not of an 

 ancestor, and perhaps for this one reason such origins would on the whole be 

 uniformly more certain of successful competition in the habitat into which it 

 was thrust by the method of its production. This series, it is true, showed only 

 recombinations, nothing in the way of new characters; but other .reactions of 

 somewhat similar nature have shown new conditions in the substance, and there 

 is no reason why in similar instances new attributes may not well be the product 

 of reactions like the one observed in the combination of these two species in 

 my experiments. 



