464 



ADAPTATION 



record on the protoplasm. This record or " engrani " is the basis 

 of memory, and the abiHty of protoplasm to retain the engraphic 

 record, i.e. its teachableness, is the basis of adaptation. " The 

 engram has a nature which is essentially dynamic. It is not to be 

 thought of as a mote left in the protoplasm by the stimulating 

 agent. It is rather a process." (Bovie.) 



No case is known where acquired characters have been transmitted 

 to offspring. 



On the other hand, the environment may have profound effects, 

 not in the nature of adaptation, })ut on the development of the 

 organism. 



Temperature. In Chap. XXXII. the effect of alterations in 

 temperature on physical, chemical and physiological phenomena 

 was considered. Temperature influences all life phenomena. 



(«) Development. One of the simplest experiments of this 

 nature ,is to determine the temperature coefficient of the develop- 

 ment of an egg. Usually the egg of the sea-urchin is chosen for 

 this purpose. Table LXXVIII. (Loeb and Chamberlain) gives the 

 time in minutes required from insemination to the first cell- 

 division for ^'arious temperatures. 



TABLE LXXVIII 



Effect of Increase of Temperature on Cell-division 

 IN Egg of Sea-ltrchin 



Increase of temperature thus causes a more rapid development 

 of the egg. 



(b) Rate of Metabolism. Increase of temperature, within 

 limits, as we have seen, causes an increase in general metabolism. 

 More oxygen is used, more carbon-dioxide is excreted, etc. Organs 

 work at a greater rate, e.g. the heart beats more rapidly. The 

 alterations of the rate of the heart of Fundalus (embryo) keeps 

 such regular pace with alterations in external temperature that 

 it could form the basis for a rough thermometer, as Table LXXIX. 

 shows. From the figures we are also justified in inferring that the 

 influence of temperature in this reaction is a function of this 

 particular temperature and does not depend on whether the 

 organism is gaining or losing heat. 



(c) The time necessary to reach sexual maturity is decreased 

 by increase of temperature. Stefansson reports that the Eskimo 



