Coleus blumei Benth 405 



apex). Since the light interruption which we gave was during this 

 period, our results suggest that interrupted night inhibits growth in 

 those plants which are initiating leaves at the time of the interruption. 

 This hypothesis is currently being tested. 



Compensatory Growth 



That auxin has no effect on compensatory growth has been shown 

 for a number of new compensatory growth experiments as well as 

 more precisely demonstrated for simple "axillaries-excised" treatments 

 (e.g., Figs. 3, 5, 6). The absence of any detectable compensatory 

 growth effect from auxin substituted for axillary shoots, old leaves, or 

 the apical bud of the debudded main shoot is the more surprising in 

 view of the widespread belief that auxin is the controlling factor for 

 the "reverse" of our basic experiment; that is, that auxin can replace 

 the apical bud in inhibiting the compensatory growth of the axillary 

 shoots (Audus, 1953, p. 162). (We are currently investigating the 

 role of auxin from the apical bud in our clone of Coleus. ) 



There are some interesting parallels between compensatory growth 

 in Coleus and in animals. In many cases excision of one animal organ 

 results in compensatory growth of the paired homologous organ (cf. 

 Weiss, 1955). For kidney, ovary, and suprarenal glands, Addis and 

 Lew (1940) reported approximately 70% restitution. Growth of 

 leaves on Coleus shoots with bud axillaries excised was of the same 

 order of magnitude, 60% of that on the controls (Fig. 5). How 

 general these relations are, remains to be seen. 



The greater growth of very young leaves when adult leaves were 

 present (Fig. 6) is reminiscent of the greater growth of particular 

 organs in chick embryos when a piece of the corresponding adult 

 organ is grafted onto the chorio-allantoic membrane (Ebert, 1954; 

 Weiss, 1955). The zoologists have found that greater growth of the 

 embryonic organ is obtained only if the grafted organ is beyond a 

 certain age. On this superficial level, at least, the phenomena are 

 similar in animals and plants. 



SUMMARY 



Excising all the axillary shoots in Coleus blumei induces compensa- 

 tory growth in the main shoot and significantly speeds flowering. One 



