86 ROBERT A. BUDINGTON. 



line. So far as bulk effect of thyroid substances on root growth 

 in A"arcissns goes, the result is the same as in Alliiim, reported by 

 the writer in '19; in general, when the control bulbs showed a 

 root length of 60 mm., the thyroid-"fed" line showed a length of 

 25 mm. These roots were then cut, fixed in aceto-alcohol, 

 stained in toto in Delafield's hjematoxvlin, and embedded. 

 Measurements of any region could be most accurately determined 

 by a study of serial cross-sections; these w r ere made 15 micra in 

 thickness. 



By count of sections, two measurements w-ere made: (a) the 

 interval from the tip of the root cap to the beginning of the 

 periblem zone ; (b) the interval from the tip of the root cap to the 

 central plerome cylinder. To illustrate the uniformity of the 

 result of such measurements, the following table is given, compiled 

 from a series of thirty roots taken at random from among 



hundreds : 



TABLE I. 



MEASUREMENTS COMPUTED FROM SECTIONS, 15 MICRA IN THICKNESS, OF Nar- 

 cissus ROOTS GROWING IN 120 cc. PFEFFER'S SOLUTION TO WHICH HAD 

 BEEN ADDED THE EQUIVALENT OF 10 GRAINS OF THYROID GLAND. 



Micra from Tip of. Micra from Tip of 

 Root to Periblem. Root to Plerome. 



1 . . . .360 405 



2. 360 420 



3 375 420 



4- -.345 405 



5 -360 420 



6.... 330 405 



7- --345 405 



.360 435 



9 -405 465 



10. . 390 480 



ii 300 360 



12 330 390 



13 .-420 495 



14 - -390 435 

 15- -390 450 

 16 330 400 



I? 405 465 



18 . .360 405 



19 330 390 



20. . . .405 450 



21 330 390 



22. . .375 420 



23. -375 420 



24 - -390 465 



25 .360 405 

 26. . . .390 465 



27 360 420 



28 390 465 



29 -390 465 



30 300 390 



