350 SCIENTIFIC ILLUSTRATIONS [Tho 



the robber, they collect their friends and neighbours in great 

 numbers, and watch the moment when the sparrow is engaged 

 in the business of incubation ; then the whole body, each bearing 

 a mass of soft earth in its bill, rushes at once to the nest, and in 

 a few moments the aperture at the top is closed by a solid mass 

 of mud, which no efforts on the part of the unhappy prisoner 

 can possibly break through. So determined are they, indeed, 

 to effect their object thoroughly, that in a case recorded by the 

 Vicomte de Tarragon, the mass of clay stuffed into the aperture 

 was nearly of the form and size of a small hen's egg, the two 

 ends projecting into and out of the nest. The sparrow was 

 found dead upon her eggs. MIL 



The Vitality of Thoughts. 



Many kinds of seeds are gifted with powers not merely of 

 retaining life under the ordinary circumstances of nature, but 

 of resisting the most terrible attacks. When wine has been 

 made from raisins, and the refuse has been scattered, over the 

 fields as manure, it has been observed that the grape-seeds have 

 vegetated and produced young vines, and this notwithstanding 

 the boiling and fermentation they have had to endure. The 

 seeds of elder-berries have been observed to grow after similar 

 trials. Many experiments have been made to ascertain exactly 

 what amount of unnatural heat seeds can bear without being 

 destroyed. It considerably exceeds that which plants can bear ; 

 and the same is the case with extreme cold. Thoughts resemble 

 seeds in many respects in their unobtrusiveness, their modes 

 of dissemination, their growth into vast things, and also, and 

 very notably, in their vital power, whereby they withstand all 

 the frosts of time and all the fires of persecution. LI. 



Thoughts Improve with the Thinker's Age. 



As the orange-tree increases in age, so the fruit improves in 

 quality, the younger trees bearing fruit with a thicker rind and 

 abundance of seeds. As the tree becomes older the skin be- 

 comes thinner, the fruit much more juicy, and the seeds diminish 

 in number. Some of the old neglected trees bear fruit of the 



