,9o8.] JENNINGS— HEREDITY IN PROTOZOA. 465 



decreases with lack of food proportionately more than does the 

 length, so that the ratio of length to breadth has fallen from 35.131 

 per cent, to 25.515 per cent. It is to be noticed, however, that this 

 greater proportionate decrease of breadth takes place in the first 

 days after the withdrawal of abvmdant food, since after the animals 

 had been only three days without new food the ratio of breadth to 

 length fell to 23.517 per cent, (row 3, Table XVIII.) ; it did not 

 decrease farther after starvation began. 



A comparative inspection of Tables VII. (page 412) and LIII. 

 (appendix) shows to the eye the very great effects of nutrition on 

 size and variation. 



Second Scries. 



After the series of experiments described above, the progeny of 

 D were kept in large culture jars of hay and water for about three 

 weeks. Then followed an exceedingly instructive series of experi- 

 ments on the effects of environmental conditions, the results of which 

 are shown in Tables XIX.-XXII. and in the large Table XVIII., 

 rows 7 to 12. Mere inspection of the correlation tables ^hows the 

 effects in such a striking way that I have placed the main tables 

 together in the text, instead of relegating them to the appendix. 



Fresh Hay Infusion. — On July 16, 1907, specimens from the 

 large cultures were placed in a watch-glass of hay infusion and 

 allowed to remain twenty-four hours. This induced rapid multipli- 

 cation ; while this was occurring a random sample of 200 specimens 

 was measured, with the results shown in Table XXX. (appendix), 

 and in row 7, Table XVIII. 



Starvation.— Isext these were allowed to starve for a week; then 

 150 specimens were measured (Table XIX., and row 8, Table 

 XVIII.). The results may be compared with our other starving 

 culture of Table LIII., and row 6, Table XVIII. It will be noticed 

 that for both length and breadth the amount of variation is not 

 great ; that the absolute dimensions are small ; that the ratio of breadth 

 to length (21.337 per cent.) is the least we have even seen, and that 

 the correlation between length and breadth is very low (.3906). 



Effects of Abundant Food on a Starving Culture. — Now this 

 starving culture (Table XIX.) was placed for twenty-four hours in 



