314 



JAMES W. McCOLLOCH AND H. YUASA 



It is interesting to note that larvae hatched from eggs laid 

 in inverted position, not only traveled longer distances on an 

 average but traveled at greater rates than those that hatched 

 from eggs laid in normal position. Table III is a comparison 

 of the rate of migration up the leaf with the rate of migration 

 down the leaf when the eggs are laid in an inverted position. 



TABLE III 



Comparison of Upward Migration with Downward Migration. 

 Eggs Laid in an Inverted Position 



Upward Journey — 



Total No. of larvae 30 



No. of larvae that got down into 



sheath 18 



No. of Isrvae that died on leaf. . . 12 



Downward journey — 



Total No. of larvae 12 



No. of larvae that got down into 



sheath 11 



No. of larvae that died on leaf. . . 1 



Average time 



required to 



move 1 mm. 



Average 

 distance 

 traveled 



3 min. 43 sec. 



4 min. 29.2 sec. 

 2 min. 35.3 sec. 



3 min. 55.8 sec. 



4 min. 10.5 sec. 

 1 min. 38.0 sec. 



50.1 mm. 



38.0 mm. 



70.2 mm. 



88.1 mm. 



89.5 mm. 

 73.0 mm. 



Thus, as the table indicates, there seems to be no marked 

 difference in the rate of progress during the journey in either 

 direction, that is, the larvae, on an average, move with equal 

 facility on either an ascending or descending incline. 



Table IV is appended in order to give a little more accurate 

 notion of the migratory rate, since these larvae were under 

 closer observation. 



TABLE IV 



Rate of Migration of Twelve Selected Larvae Hatched from 

 Eggs Laid in an Inverted Position 



