188 WONDERS OF ORGANIC LIFE. 



whether for a season or for a permanent union 

 — beings which are social, not only form 

 assemblages, but labour conjointly, instinct- 

 directed, to effect some definite purpose. In- 

 stinct does not bring plants together, but it 

 does make animals seek each other's society. 

 The seeds of a plant fall around it — if the soil 

 and air be congenial, a congregation is the 

 result ; but truly gregarious beings seek each 

 other out, and form a body politic. Now, shoals 

 of fishes, hordes of Crustacea, springing from 

 multitudes of eggs deposited in a given locality, 

 may to a certain extent be compared to what 

 baron Humboldt terms social plants. Yet at 

 the same time there is this difference ; they 

 instinctively associate together for the purpose 

 of visiting feeding-grounds in rivers, or of 

 migrating from the deep sea to shallower water 

 near the shore. Some fishes, however, may be 

 regarded as solitary, although of these the 

 young fry congregate together in multitudes; 

 but even here the congregation is rather the 

 effect of circumstantial necessity than of choice. 

 A colony of rooks or herons presents us with a 

 a well-ordered republic, but this cannot be said 

 of a shoal of mackerel or herrings, nor even of 

 a cloud of locusts. At the same time, it is 

 difficult to draw a strict line between animals 

 which congregate together and those which are 

 gregarious, for we can scarcely tell how far 

 association is coveted for the sake of association 

 alone, or how far instinct leading animals to 

 the same ultimate objects renders their asso- 



