UNSOLVED PROBLEMS. 155 



scribed by Mrs. Burton, pass on a stranger under their escort 

 from one dog sentinel to another. 



In many animals there are periodical assemblages of 

 great numbers, sometimes from all points of the compass, 

 of the object of which, and the nature of the singular pro- 

 ceedings that frequently characterise them, we must also be 

 said to be ignorant. Some of these assemblages and pro- 

 ceedings in birds are believed to be judicial, and their 

 observers have described judges, jury, culprit, advocates, 

 officers of court, conviction, condemnation, and summary 

 punishment. But in other cases such a supposition does 

 not explain the phenomena. Thus a writer on the habits 

 of the Indian crow says, ' In addition to their bathing as- 

 semblages, they have remarkable parliaments .... always 

 held in quiet, out-of-the-way places, and always on the 

 ground. . . . The proceedings are absolutely silent, and 

 seem mainly to consist in small knots of individuals ex- 

 hibiting their graces before one bird. They will hop round 

 him iii various attitudes, look at him first with one eye, 

 then with the other, and all the while the central in- 

 dividual will be supremely indifferent to their attentions. 

 Perhaps the proceedings will be varied by a disconcerted 

 crow hopping to another group, there to exhibit his or her 

 charms. This silent session will be maintained for an hour, 

 and then suddenly break up with loud cawing, just as if the 

 crows were being released from a disagreeable duty and 

 were rejoicing in their escape. I never could make out what 

 these assemblages are for. They are not amatory, for they 

 occur as often after as before the breeding season, and they 

 are not judicial, for they are absolutely silent and 110 results 

 follow.' 



There are many curious companionships or attachments 

 between animals of different species and genera, including 

 those between the lower animals and man, the cause, origin, 

 or object of which does not appear, if indeed any intelligible 

 motive can be said to exist. In some cases there has been 

 an intelligible cause, such as gratitude for benefit, or desire 

 for protection or for co-operation in defence ; but in many 

 others the only explanation that suggests itself and it can 



