v FLUCTUATION 97 



ably primitive cottons as G. Sturtii, F.V.M.,* retain the 

 entire leaf throughout their development. 



The depth of the segmentation, when present, varies 

 within the same sub-species, as in the two forms of 

 " Nyam-nyam kidney cotton ; " possibly the Okra-leaf 

 sport in American Uplands is another example. Such 

 facts are suggestive of mutation, but mutations in 

 Gossypium ought not to be mentioned until we know 

 much more about natural crossing and heredity than we 

 are likely to acquire for several years to come. 



The flower. In the course of an attempt to breed 

 an uncrossable flower, to be mentioned again later, the 

 author had had occasion to measure the various floral 

 organs, namely, petal, style, staminal column, and fila- 

 ments. The sequence of development of these in the bud 

 begins with the petal, followed by the column .and fila- 

 ments, and ends with the style. 



The fluctuation does not follow this order. Fifty-one 

 plants in " 77 " family gave the following typical 

 results : 



Petal Mean, 59 mm. P.E. 2' 8 per cent. 



Style 33 P.E. 3'5 



Column 19 ,, P.E. 5'6 ,, 



Filament ... .,. ,, 4'2 mm. P.E. 77 ,, 



A portion of this increased fluctuation is probably 

 apparent, being due to greater errors of measurement in 

 the smaller organs, but much of the increase is certainly 

 significant. One would rather expect the external organs 

 to fluctuate most, but the reverse is the case. 



The involucral bracts are intermediate in their fluctua- 

 tion. Their width in the same family gave a P.E. of 

 -t 4*0 per cent. The ratio of width to length also gives 

 a 4'0 per cent, probable error. 



The measurements are taken with dividing compasses 



* Watt, Sir G. 



