32 MANUAL OF ZOOLOGY. 



sequent development of these fecundated ova into workers or 

 queens depends entirely upon the form of the cell into which 

 the ovum is placed, and upon the nature of the food which is 

 supplied to the larva. So far there is no doubt as to the nature 

 of the phenomena which are observed. It is asserted, how- 

 ever, By Dzierzon and Siebold, that the males or drones are 

 produced by the queen from ova which she does not allow to 

 come into contact with the semen as they pass through the 

 oviduct. This assertion is supported by the fact that if the 

 communication between the receptacle for the semen and the 

 oviduct be cut off, the queen will produce nothing but males. 

 Also, in crosses between the common honey-bee and the Ligu- 

 rian bee, the queens and workers alone exhibit any intermediate 

 characters between the two forms, the drones presenting the un- 

 mixed characters of the queen by whom they were produced. 



If these observations are to be accepted as established, and 

 upon the whole there can be no hesitation in accepting them 

 as in the main correct, then the drones are produced by a true 

 process of parthenogenesis ; but some observers maintain that 

 the development of any given ovum into a drone is really due 

 as in the case of the queens and workers to the special cir- 

 cumstances under which the larva is brought up. 



There are various other cases in which parthenogenesis is 

 said to occur, but the above will suffice to indicate the general 

 character of the phenomena in question. The theories of par- 

 thenogenesis appear to be too complex to be introduced here ; 

 and there is the less to regret in their omission, as naturalists 

 have not yet definitely adopted any one explanation of the 

 phenomena to the exclusion of the rest. 



First Law of Quatrefages. From the phenomena of asexual 

 reproduction in all its forms, M. de Quatrefages has deduced 

 the following generalisation : 



" The formation of new individuals may take place, in some 

 instances, by gemmation from, or division of, the parent-being ; 

 but this process is an exhaustive one, and cannot be carried 

 out indefinitely ; when, therefore, it is necessary to insure the 

 continuance of the species, the sexes must present themselves, 

 and the germ and sperm must be allowed to come in contact 

 with one another." 



It should be added that the act of sexual reproduction, 

 though it insures the perpetuation of the species, is very de- 

 structive to the life of the individual. The formation of the 

 essential elements of reproduction appears to be one of the 

 highest physiological acts of which the organism is capable, 

 and it is attended with a corresponding strain upon the vital 



