TEE INTERPRETATION OF NATURE 129 



nature that has been poured upon this generation, the whole thing has 

 come about from a certain unappeased popular demand. There is a 

 widespread and rapidly growing curiosity about and interest in animate 

 beings. Such curiosity and interest lead inevitably to efforts for in- 

 creased knowledge. The authoritative biology of the day has failed and 

 is failing to meet this demand. 



Let any teacher of botany or zoology in school or college, whose ex- 

 perience reaches back twenty years, consider the men and women of to- 

 day who were once his pupils. Let him ask himself to what extent his 

 efforts succeeded in making the plants and animals by which these men 

 and women have since been constantly surrounded, vital, potent, 

 perennial elements in the effectiveness of their lives. Testing your 

 work thus, does the voice of conscience say well done? It surely does 

 not for me, and I have no reason to suppose the instruction I gave 

 during some fifteen years to general classes in the University of Cali- 

 fornia was particularly worse than that given by most teachers. I 

 made use of the regulation paraphernalia in the regulation way. There 

 were the innumerable wall-charts carefully drawn and colored, with the 

 proper conventions for ectoderm, mesoderm and entoderm, and for the 

 various cell-parts during indirect cell-division, fertilization, and so 

 forth. A fairly complete set of preparations to illustrate the lectures 

 was at hand, some in bottles, some dry. The fundamental nature of 

 living substance, " according to the latest and best authorities," and 

 the fundamental difference between plants and animals, were early and 

 concisely set forth. Near the beginning of the course the doctrine of 

 evolution was made clear and impressive, and strong enough to sustain 

 the weight of every fact that should later be brought forward. 



The vast importance from the evolutionary standpoint of a few 

 fundamental types, amoeba, volvox, the calcareous sponges, the primi- 

 tive annelid, Amphioxus, the shark, was duly insisted upon. The gas- 

 trula, the coelome, the nephridia, the somites of the vertebrate head, 

 and the rest of the thirty-nine articles of evolutionary faith were set 

 forth. The " factors " of evolution were treated with generosity. 

 Natural selection was of course given first place, but later mutation 

 became its close second. Not only colored figures, but an actual speci- 

 men, naturally environed in a glass case, of Kdilima, that wonderful 

 leaf-butterfly which has been the cornerstone of a whole philosophy, 

 was provided to illustrate protective resemblance; and various other 

 instances of adaptation were shown. When the topic of animal psy- 

 chology was reached, it was pointed out how easily and completely the 

 tropism theory disposes of the vagary of earlier notions about the 

 intelligence of lowly creatures, and the interesting point was made that 

 in a simple caterpillar " reacting " up a stick we probably have in our 

 hands the key to the whole mystery of mind in the living world. 



