28 SUMMARY OF CURRENT RESEARCHES RELATING TO 



not a parasite of Aphides, as its name suggests, but lays its eggs in dead 

 Aphides containing the larva of a Braconid (Aphidius brasskse Marsh), 

 or this larva already parasitised by a Cynipid (AUotria vittrix West, var. 

 infuscata Kieff). As in Litomastix and Ageniaspis the completely 

 developed oocyte of the first order has a nucleus anteriorly and a nucle- 

 olus posteriorly. The non-fertilised eggs develop into males. There 

 are always two polar bodies, which play no part in development. The 

 nuclei divide in segmentation, but the ooplasm remains undivided. 

 In the cell which receives the nucleolus and in its descendant cells there 

 is a retardation of multiplication. The ovum gives rise to only one 

 embryo. 



In Oophthora semblidis, which develops in the eggs of Mamestra 

 brasskse, the sequence of events is very much the same as in Encyrtus, 

 but the form of the larva is very different. 



Biology of Myrmecophila.* — F. Schimmer publishes a contribution 

 towards a monograph of the genus Myrmecophila Latr. He deals 

 mainly with the forms found in ants' nests, especially with M. acervorum, 

 which was the only species that could be procured alive and kept under 

 observation. Only eleven forms of Myrmecophila are known, but these 

 are distributed over all five regions of the earth. M. prenolepidis and 

 M. americana Sauss. are identical. Wasman's hypothesis of transporta- 

 tion is probably the true explanation of the wide distribution of this 

 form. Although, as has been already established, all the myrmecophilous 

 crickets, with the possible exception of M. americana, may be found 

 associated with several hosts, yet in each region of their occurrence a few 

 species of ant seem to be preferred ; thus M. acervorum is usually found 

 in the nests of Lasius niger, and in suitable localities of Myrmica rubra. 

 The reason for this preference is probably an adaptation in the relative 

 size of host and guest. The biological reason for the symbiotic relation is 

 to be found in the protection and food that the crickets find in the nests 

 of their hosts. They get this food in several ways : by licking the auts, 

 by robbing the workers returning to the nest with stores, or the newly 

 fed larvae, by sharing in the feeding of two or more ants, or, finally, they 

 may be fed directly by the ants. The psychological basis of the relation 

 lies in the different instinct mechanisms of the guests, not of the hosts 

 (instincts of licking, of plundering, of demanding food). The 

 mechanisms of movement which come into play in this symbiotic 

 relationship are, on the one hand, of a mimetic nature (imitation of 

 the ants 1 social instincts : the cleaning instinct, the demanding food by 

 raising the forelegs, and the imitation of the movements of the 

 antennai) ; on the other hand, they are contrary to the corresponding 

 mechanism of movement in the ants (circular, instead of straight move- 

 ment, and power of leaping). The co-operation of these two kinds of 

 movement secures for the crickets an apparent toleration on the part of 

 their hosts. Both mimetic and contrary movements may, under favour- 

 able conditions, fail of their effect even with the true host, and they 

 may produce the same or a similar effect on strange ants, as they nor- 

 mally do on the host. 



* Zeitschr. wiss. Zool., xciii. (1909) pp. 410-531 ( 3 pis. and G figs.). 



