Care of the Young in the Animal Kingdom. 165 



hatched. 1 I know some colonies of Formica san- 

 guinea, near Exaten, in which these pseudogynes sud- 

 denly made their appearance, became more numerous 

 in the course of the next few years, and gradually 

 decreased later on, or disappeared entirely. One 

 colony (No. 21) in 1895 reared every possible pseu- 

 dogyne intermediate form between normal workers 

 and normal queens ! Since the queens which lay the 

 eggs in these nests are unable to change at will the 

 nature of their ovaries from year to year, but are 

 always compelled to lay fertilized eggs, capable of 

 equal development, the origin of those intermediate 

 forms is probably due to changes in the manner of 

 nursing, and to modifications in the very nursing 

 instincts of the workers. This supposition is con- 

 firmed by the fact, that in F. sanguinea there is a 

 certain causal relation between the origin of pseu- 

 dogynes and the education of the larvae of a genuine 

 ant- guest, the beetle Lomechusa strum osa. I have 

 ascertained this mysterious connection by means of 

 my statistics embracing 410 sanguinea colonies within 

 a radius of several kilometers around Exaten ; these 

 statistics will be published later on in some scientific 

 periodical. 2 Here it may suffice to mention, that the 

 centres of propagation of the pseudogyne forms and 

 of the Lomechusas are always together in the same 



1 ) See my recent publication, "Neue Bestaetigungen der Lotnechusa- 

 Pseudogynen Theorie" ("Verhandl. der Deutsch. Zool. Gesellsch.," 1902, 

 pp. 98-108 and PI. II), where this theory is extended also to North 

 American ants. See below (the following section, p. 179 foil, and the 

 plate opposite p. 181). 



*) The beginning of those statistics dates back to 1895 ("Die 

 ergatogynen Formen bei den Ameisen und ihre Erklaerung," "Biol. 

 Centralbl.," 1895, Nos. 16 and 17). 



