ins 



THE AMEJHCAX MUSEUM JOURXAL 



PERSISTENCY OF TYPE 



All inliabitant (2I(ihiria f.iiiuift'ra, 

 at the left) of tlie seas many mil- 

 lion years ago (mid-Cambrian), pre- 

 sented for comparison with its 

 modern descendant, the common 

 liorseshoe crab {L!nii(li<s) . — They 

 well illustrate adajitation to their 

 sand and water environment, and 

 also the persistency of a type 

 tlirough vastly long periods of time. 

 In such an e.xample of evolution 

 (visible of the body and invisible of 

 the germ), the body has been iu 

 direct contact with the forces of the 

 inorganic and the living environ- 

 ments ; the heredity-chromatin of the 

 germ has been remote from contact 

 with external environments. Pro- 

 fessor Osborn records that, never- 

 theless, the study of prehistoric ani- 

 mals tends to prove that the evolu- 

 tion of the heredity-chromatin. while 

 slow and prolonged, always is di- 

 rected toward adaptation of the 

 species to its life in the given en- 

 vironment. 



A geologic estimate made in 1899 

 (Geikie). of the age of life, or of 

 the earth since bacterial life appfiirfd. is lioiii out- hundred to four hundred million years: an estimate 

 made in 1909 (SoUas) gives from thirty-four to eighty million years. These estimates were made by 

 computing, at rates of deposition today, the limestone and other deposits due to the work of bacteria 

 (followed later by other mineral-depositing life forms, algae, diatoms, protozoans, and mollusks). 



Whether chromatin is as old as the bacteria, or in fact whether it exists in the bacteria of today, 

 is a disputed question. It is the opinion of the author, following that of Wilson (Columbia University, 

 New York) that chromatin is as old as protoplasm, and that it takes its place with protoplasm as one 

 of tlie two great tangible elementary structures of all life even unto man. 



OFFENSIVE AND DEFENSIVE ADAPTATIONS 



The carnivorous "tyrant" dinosaur ( Ti/raiinosaurus) (it towers about 18 feet from the ground) is 

 approaching a group of horned herl)ivorous dinosaurs (Ceratopsia) . 



I'he Orif/in and Evolution of Life discusses the theory of the beginning of life as a recombination 

 of energies and elements preexisting in the cosmos. It puts forth the idea that there is an energy 

 control of life, that energy is the cause of evolution, that some combination of energy always precedes 

 and molds form in the living world. We recognize that invisible energy lies back of the phenomena of 

 the electric train and of wireless telegraphy ; it is possible that the energy transmitted from the micro- 

 scopic chromatin, acting in an infinitely com])lex and. to us, mysterious way. can control the develop- 

 ment of a giant tree or a dinosaur. 



The author emphasizes that it is the function of life to "capture" energy wherever it can be found 

 and to utilize it. Earliest forms of bacterial life, feeding directly on inorganic matter, used heat energy 

 from the sun; green plants capture light and heat energy (they can make starch only in sunshine), 

 storing these within themselves in passive form (in starches, oils, sugars, etc.) which the animal retrans- 

 forms into active energy when the plants are used for food. The giant dinosaurs were the climax in 

 capture, storage, and release of energy. The evolution of the defensive types proceeded step by step 

 with that of the offensive types, producing an example of counteracting evolution similar to that in 

 Xorth American wolves and bison or deer. This approach by Osborn to life and evolution through a 

 study of energies primarily and of matter and form secondarily sets a direction for future researches 

 by the many — instead of by the few as in the past 



