While upon the subject of memory in the Hymenoptera, it is indispensable that we should again refer to the observation of Messrs. Belt and Bates already alluded to on pages 150-51. For it is from that observation rendered evident that these sand-wasps took definite pains, as it were, to _teach themselves_ the localities to which they desired to return. Mr. Bates further observed that after thus taking a careful mental note of the place, they would return to it without a moment's hesitation after an absence of an hour. The observation of Mr. Belt, already quoted _in extenso_, proves that these mental notes may be taken with the utmost minuteness, so that even in the most intricate places the insect, on its return, is perfectly confident that it has not made a mistake. With regard to the duration of memory, Stickney relates a case in which some bees took possession of a hollow place beneath a roof, and having been then removed into a hive, continued for several years to return and occupy the same hole with their successive swarms.[50] Similarly Huber relates an observation of his own showing the duration of memory in bees. One autumn he put some honey in a window, which the bees visited in large numbers. During the winter the honey was taken away and the shutters shut. When they were again opened in the spring the bees returned, although there was no honey in the window. These two cases amply prove that the memory of bees is comparable with that of ants, which, as we have seen from analogous facts, also extends at least over a period of many months. _Emotions._ Sir John Lubbock's experiments on this head go to show that the social sympathies of bees are even less developed than he found them to be in certain species of ants. Thus he says:--