252 LEISURE-TIME STUDIES. 



prove that form and appearance are most deceptive and 

 utterly unreliable aids in the task of distinguishing between 

 the animal and plant creations. Even animals of a high 

 grade are seen to present a striking resemblance to plants ; 

 and when we ascertain that the truly animal nature of the 

 well-known coral-polypes was first ascertained only some 

 hundred and fifty years ago, we can readily appreciate the 

 fact that the separation of the two great groups of living 

 beings was a task which proved of somewhat trying nature, 

 even for the scientific acumen of a tolerably advanced age. 



A very natural appeal might be made to the chemist and 

 microscopist for aid from their respective sciences in the 

 task before us. The subtle nature of chemical tests, and 

 the delicate investigations of the microscopist, might, with 

 every appearance of reason and with great hopes of success, 

 be relied upon in the endeavour to find the distinctive 

 marks of plant and animal character. But neither the 

 chemist nor the microscopic investigator can produce a 

 "philosopher's stone" which shall enable us to separate 

 animal from plant. On the contrary, both sciences contri- 

 bute to the general confusion of substance which apparently 

 exists in the lower domains of living nature. The chemist 

 will tell us that he knows of no one element or compound 

 which can be said to be characteristic of either amimal or 

 plant series ; whilst he is forced to admit that if he had to 

 judge certain well-known animals by a purely chemical 

 standard, he would be forced to conclude that they were 

 true plants. For example, the old ideas that the element 

 nitrogen was characteristic of animals, and that carbon was 

 a substance belonging exclusively to plants, have been long 

 disbanded, in the light of the certain knowledge that these 

 elements unquestionably enter into the composition of both 

 groups of living beings. Nor is this latter the only point 

 which the advance of chemistry has corrected. Certain sub- 

 stances long thought to be absolutely peculiar to animals in 

 the one case, or to plants in the other, have been discovered 

 -entering into the intimate and apparently natural composi- 



