HOW A NATURALIST IS TRAINED. 639 



formed were arranging themselves in layers and building up tbe em- 

 bryo. Such scenes as these have a fascination beyond description, and 

 the student can not repress the feeling that, could he wait a little longer, 

 or were his microscope a little more powerful, he could actually see 

 the force that accomplished these marvelous results. On the morrow, 

 when he returns to his study, the feeling is the same, and no matter if 

 he be witnessing some phase of development, even for the hundredth 

 time, he is as interested as at first. At such times it seems as if the 

 solution to the great problem, " What is life ? ". were really close at 

 hand. 



So far it has been an easy task to describe the process of conversion 

 of an untrained person into an original investigator, but there is an- 

 other side — a psychological one — which baffles description. All that is 

 necessary in order to perform the various operations which have been 

 thus briefly outlined are power of observation and skill in manipula- 

 tion ; but the facts thus gained must be interpreted in order to render 

 them of real value. A paper which merely details the facts observed 

 of course has its value ; but if it adds a comparison of them with the 

 phenomena which occur in other forms, and tells or even suggests 

 their meaning, it then takes a far higher rank. This, however, takes 

 thought, and who can describe the way in which one thinks ? 



The student tries to master every fact in the development of his 

 embryos, and then compares these facts with what was already known 

 of the development of other forms. In this way he recognizes simi- 

 larities and differences, for both of which explanations are to be 

 sought. Even in the development of the specimen studied there are 

 many phenomena which have their own meaning, and which, properly 

 interpreted, throw much light on its ancestry and line of descent. In 

 general terms this interpretation is effected by framing an hypothesis 

 which will embrace some of the facts, and then testing it in every con- 

 ceivable manner. When an objection arises, the first step is to see if it 

 really be founded on fact, or upon a misconception, and then, if it be 

 valid, the attempt is made to reconcile it with the hypothesis. It fre- 

 quently happens that several hypotheses are formulated before a satis- 

 factory one is found. 



Such in brief outline is the training, or rather a part of the training, 

 which is necessary to make a naturalist to-day. The time is past when 

 one can collect a few bugs or shells and then straightway proceed to 

 describe so many new species. Description of species is a necessary 

 work, but it is not the highest kind of work. Far more important, far 

 more ennobling, far more interesting are the deeper problems of how 

 an animal grows, why it grows in the way it does. The training neces- 

 sary for work of this character requires as long a time, as much pa- 

 tience, and as much perseverance as does any of the so-called learned 

 professions ; but when one becomes an original investigator there is 

 no respite. It means continual work, continual study. If one stop, 



