38 SCIENTIFIC ILLUSTRATIONS [Cha 



stronger, and more beautifully clouded than in any other turtle. 

 The removal of the plates is a very cruel process, the poor 

 reptiles being exposed to a strong heat which causes the plates 

 to come easily off the back. In many cases the natives are 

 very rough in their mode of conducting this process, and get 

 the plates away by lighting a fire on the back of the animal. 

 This mode of management, however, is injurious to the quality 

 of the tortoiseshell. After the plates have been removed, the 

 turtle is permitted to go free as its flesh is not eaten, and after 

 a time it is furnished with a second set of plates. These, 

 however, are of inferior quality, and not so thick as the first 

 set. NA. 



A Casuist's Defence. 



A peculiar organ possessed by many Cephalopoda is the ink- 

 bag, a small pyriform sac, which secretes a dark-brown fluid ; 

 its contents may be discharged into the water, which is thus 

 discoloured for a considerable extent. When attacked, the 

 animals constantly employ this artifice to facilitate their escape, 

 the inky secretion producing a thick cloud in the water, under 

 cover of which the cuttle-fish rapidly retreats to a safe distance 

 from the object which has excited his apprehensions. He saves 

 himself by this mystification. The mind of a casuist performs 

 an analogous feat when hard pressed in argument by an opponent. 

 It is wont to envelop itself in a thick cloud of words. Under 

 cover of their hidden meanings the casuist withdraws in great 

 dignity, and the disputant, who would have been his match in 

 a clear controversy, is left alone in defeat. N. H. 



The Greatest Cemetery. 



The crust of our earth is a great cemetery, where the rocks 

 are tombstones on which the buried dead have written their 

 own epitaphs. si. 



The Instinctive Love of Change. 



The quail, even when born in captivity and domesticated, 

 burns with that instinctive love of change which distinguishes 



