CORRESPONDENCE. 183 



[We much regret that we are unable to complete Mr. Tuffen West's 

 valuable Notes in the present issue. The remainder, with the 

 "Selected Notes from Note-Books " having reference thereto, with 

 the explanation of Plates XVI., XVII., and XVIIL, will be 

 given in our next. — Editor?^ 



Corrceponbcnce. 



\The Editor does ?iot hold himself responsible for the opitiions or 

 statements of his co-respondents^ 



Sir,— 



In the Journal of Microscopy, etc., for April, Mr. Wheatcroft 

 draws special attention to the fact that in studying the plant- 

 remains found in Egyptians tombs, Dr. Schweinforth has not 

 been " able to detect any peculiarities in the living plants which 

 are absent in those obtained from the tombs." Mr. Wheatcroft 

 says these specimens were gathered at least four thousand years 

 ago, and he thinks it " would be difficult to produce better 

 evidence of permanency of type." Precisely this argument was 

 used with reference to the theory of permanency of type in 

 animals. We v/ere told that the domestic cat, whether in the 

 mummical state or in its pictured representations, was just the 

 same in that remote Egyptian age as it is at the present day. 

 But we know now that instead of finding permanency of type as 

 the prevailing law amongst animals, we find species and orders 

 fading into one another like dissolving views as we penetrate 

 further back into the abyss of time. The changes are very 

 gradual ; to lose a tooth would be far too sudden a transition. 

 One cusp disappears, and then another ; then the tooth appears 

 later, grows smaller, decays early, and finally disappears altogether. 

 The same gradual changes occur in the modifications of the whole 

 skeleton, but most noticeably in the limbs. The cat, so " exactly 

 like " our cat of the present day, changes by almost imperceptible 

 degrees into an animal which is neither cat nor weasel, but the 

 progenitor of both ; the dog into an animal which is neither bear 

 nor dog, but which has some characteristics of the two modern 

 species. 



It is difficult to imagine how any paleontologist of the present 

 day could expect that an animal would be likely to change 

 perceptibly in such a brief second of geological time as four 

 thousand years. The whole of the Tertiary period can only be 



