IO ENTOMOLOGICAL NEWS [Jan., '14 



plants. The difficulty to be overcome in these groups arises 

 from the presence of a large number of the transitional forms 

 and individuals that are always produced during the evolution 

 of stocks. What is to be done in such case? It is clear that 

 what suffices to meet the requirements of the one case will 

 not meet the quite distinct requirements of the other. The 

 species-concept must therefore be modified to such extent as 

 is necessary for adapting it to the requirements of each case. 



It has long been held that a species comprises all individuals 

 whose interbreeding will produce fertile offspring. This can 

 not now be accepted. Plants, insects, and even mammals, 

 which the majority of biologists will agree are entitled to spe- 

 cific recognition, possess this power. We have only to recall 

 the plants which have been successfully hybridized within 

 recent years and insect species which have mated and pro- 

 duce fertile progeny. It is quite possible to secure fertile 

 offspring from the union of certain distinct but closely allied 

 species of flies, butterflies and beetles whose' external sexual 

 organs admit of mating. Instances of hybrid insect races are 

 on record. It is not within the limits of this article to cite 

 cases, but the records show it to be practically beyond question 

 that in certain instances the spermatozoa of one species have 

 the power to fertilize the ova of another and produce there- 

 from fertile individuals. Other definitions of species so far 

 given, aside from the above, also fail to apply in young stocks. 



The keynote of all biological investigative work is to verify 

 and record faithfully the results of one's investigations. Such 

 results form a sure basis for further investigations. It is 

 certain that all systematists do not yet fully realize the sig- 

 nificance of some of the unchallenged results so far obtained. 

 As a profitable though outre illustration, true nevertheless to 

 living conditions, we may imagine an immense extent of fertile 

 land surface covered with a varied and teeming flora and fauna 

 still more or less in process of evolution and subjected to all 

 the varied combinations of conditions that will support life, 

 We may further imagine for the moment that we are not only 

 intimately acquainted with each of the practically innumerable 



