No. 6.] PROPORTIONATE STRUCTURES IN STENTOR. 319 



a good deal of variation in the proportion between the width of 

 the peristome and the length of the animal both for small 

 normal individuals and for those that have come from anterior 

 pieces, it may be stated that pieces from the anterior end may 

 produce new stentors whose proportions come within the 

 range of variation of size of normal small stentors of about 

 the same length. The measurements of posterior pieces, that 

 are at first too long for the size of the peristome, show that 

 they, too, assume more typical proportions. Thus one of the 

 posterior ends of the last series measured, on February 6, 

 i .o x .25. On February 10, two other individuals in the same 

 list measured 1.4 x .38 ; 1.2 x .4. The peristomial region had, 

 therefore, reached the full size. 



A somewhat crude comparison may bring the results home. 

 If a man were cut in two at the waist and the pieces behaved 

 in the same way as those of stentor, two new individuals 

 would develop. The anterior half would produce a small man 

 with a head too large for his height, i.e., his legs would be too 

 short for a man with that sized head. Although the old head had 

 grown smaller, it would be still too large for the rest of the new 

 man. In fact, his proportions would be more like those of a 

 baby whose head is relatively too large for his length as com- 

 pared with that of a man, and his legs too short. It is just 

 this result that we have found for anterior pieces of stentor. 

 If the new man were supplied with food, all parts of the body 

 would grow larger ; but as he got larger his legs would grow 

 faster than his head. 



The posterior end of our imaginary man would have at first 

 legs too long for his total length, and his new head would be 

 relatively too small ; but if he were fed his head, shoulders, and 

 arms would grow faster than any other part and continue to 

 grow until the proportionate size had been reached. If he were 

 not fed, it is possible that his head and upper part might 

 increase more slowly in size at the expense of the material in 

 his legs, and the latter would get smaller until a balance 

 was reached. The result would be that a boy rather than a 

 baby was produced. 



In other experiments pieces were removed that contained 



