550 THE AMERICAN NATURALIST [Vol. LVI 



tion. The vitalist will now come forward and claim that 

 the organism is not constituted by parts simply fastened 

 together at certain points, that its unity is the cause of 

 its function; the mechanist will be inclined to doubt the 

 possibility of whole organs regaining their function 

 by ''exchange" in animals without high regenerating 

 power, for he has been trained to believe in the destruc- 

 tion of function by the severing of the nerve. 



Let us turn to facts. Certain animals, widely distrib- 

 uted through the animal kingdom, practise the faculty of 

 shedding appendages or other parts of their body at cer- 

 tain preformed breaking points. This "autotomy" is 

 also observed in the Crinoid, Antedon rosaceus. Work- 

 ing at the Naples Station in 1900 on the regeneration of 

 'these Crinoids I wanted to find out if the color in regen- 

 erating arms would be influenced by the color of the vis- 

 ceral mass. Now Antedon shows a great variety of very 

 distinct shades, such as bright yellow, carmine red and 

 chocolate brown. The visceral mass, easily shed by the 

 animal, was transplanted in proper orientation to a speci- 

 men of different color, also void of its viscera. It was 

 immediately accepted by the new owner and clutched 

 tightly to the calyx, as is the usual thing with the normal 

 animal. The connections between the new visceral sac 

 and the body were soon restored, the exchange succeeding 

 in every case. Mouth and anus, both situated on the sur- 

 face of the visceral sac, became functional again. It is 

 clear that here there is a case of the fourth method of the 

 engineer, namely the replacement of a missing part by a 

 new one of exactly the same form fixed in at the same 

 connecting points as before. One difference is apparent : 

 in the machine there w^ill be little if any activity on the 

 part of the receiver or the new part, whilst in the Crinoid 

 the newly fixed parts are reunited by internal forces. If 

 we w^ant to understand the " exchange " followed by func- 

 tion, it is therefore necessary to know the nature of these 

 forces. Is it possible to account for them on the ground 

 of our present knowledge of living matter! Can we con- 



