TRANSMISSIBILITY OF FUNCTIONAL MODIFICATIONS 93 



degeneration of the ovaries. Many of them were very small, only 

 5 mm. in length, and had probably received very little food, and, 

 according to the theory of direct influence, these should have been 

 pure workers. That they possessed the head and thorax of a queen 

 is a proof that the characters of both forms of individual were 

 present in the germ-plasm as primary constituents, or indeed entire 

 ids. In normal circumstances only one kind of these ids would have 

 become active, either the worker-id or the queen-id, but in abnormal 

 circumstances they might both be liberated to activity simultaneously, 

 and then they would stamp one part of the body with the character of 

 a queen, another with that of a worker. Forel observed one of these 

 nests in two successive years, and both times found the mixed forms 

 in large numbers^. In the second year he found a great number 

 of newly-emerged individuals of this tj^pe. I have already inferred 

 from this observation that the mixed for-ms were probably in both 

 j-ears the offspring of the same mother, and this may well have been 

 the case. My further conclusion, that the mixed forms must be due 

 to some abnormality in the constitution of the germ-plasm of the 

 maternal eggs, no longer appears to me so convincing as it did 

 formerlj', because, in the interval, we have learnt, through that 

 indefatigable investigator of ants. Pater Wasmann, that there is 

 another possible explanation of these mixed forms ; it, too, is based 

 upon a hypothesis, but it is so interesting that I must briefly outline 

 it to you. 



Like Forel and myself. Pater Wasmann had supposed that the 

 reason of this kind of mixed form (the so-called pseudogynous worker) 

 lay in an abnormality of the constitution of the germ-plasm, but he now 

 regards it as the result of a change in the mode of rearing instituted by 

 the workers with respect to the constitutionally female or queen larvae, 

 because there was a scarcity of workers. The hypothesis sounds very 

 daring, but it is well founded, at least m so far that there really is 

 a reason why a scarcitj^ of females must occur at certain times in 

 some colonies of ants, and this might certainly determine the workers 

 in charge of the larv^ to feed females with worker food, so as to rear 

 them to render the necessary assistance. 



This reason lies in the occasional presence of a parasitic beetle, 

 Lomechusa strwniosa, whose lai'vse, curiously enough, are cared for and 

 fed by the ants as though they were their own, and in return they 

 eat up the larvje of the ants, often destroying them in large numbers. 



' There are different kinds of ' mixed forms ' among ants, which may owe their 

 origin to a variety of conditions, as Forel, Wasmann, and Emery have shown in 

 detail. 



Digitized by Microsoft® 



