No. 639] 



GHOWTII AND NUCLEAR DIVISION 



341 



6. By the time one of the nuclei of the six-nucleated 

 stage has been stimulated to division the average area 

 per nucleus increases again to 172.1 sq. mm. After this 

 division is completed and seven nuclei are present, two 

 of them small, the average area per nucleus, as was to be 

 expected, decreased to 141.9 sq. mm. During the period 

 necessary for the two small nuclei to reach their full size 

 (Fig. 8) the area increases again to 152.4 sq. mm. A fur- 

 ther increase to 168.1 sq. mm. occurs by the time sufficient 

 growth takes place to stimulate one of these seven nuclei 

 to divide, and a decrease (to 141.0 sq. mm.) again takes 

 place wiien this stage evolves into that with eight nuclei 

 (Fig. 9). 



The two curves in Fig. 18 show clearly tlie increase in 

 area per nucleus up to tlic jxiint where one iincleiis di- 

 vides, then a consi)i(-uon> decren-e t'ollowinu' nuclear 

 division, and subseqiienl l\- an Increase durin-- the pei'iod 

 when tlie mwUn resultin.u from division re-ain their full 



