182 STMDIES IN INDIAN SUOARCANK SEEDLINGS 



CANE MODULE AND SUCROSE. 



Correlation 6. 



The module of the stem, as in the leaf, is the length divided by the thick- 

 ness, but the resultant is one of averages and not of extremes as in the leaf 

 measurements. There is a distinct positive correlation between cane module 

 and sucrose iji the larger series, Chiftan and Karim, which is all the more to 

 be noted when we remember tlie irregulaiities in the two preceding tables. 

 The others of the general series fall more or less into line, excepting Cheni, 

 whose length measurements have, however, been already stated to be untrust- 

 worthy (p. 180). It is noteworthy that the Vellai cross disagrees with its allies 

 on other occasions, N<i(tn<d and the Shdldtch/jnid cross, and shows a distinctly 

 positive correlation. On the other hand, the two latter agree remarkably. 

 in each case with a maximum in the second class followed by a decline in the 

 third and fourth, a featuie of perhaps no importance and merely a coincidence, 

 but worthy of note in passing. 



The measurements of leaf and stem have now been fairly fully studied 

 in their relation to the (|uantity of sucrose in the juice. From this stu'ly it 

 would appear that the seedlings, in any general collection, with higher sucrose 

 content, would be marked out by rather narrow, short leaves, but with a rela- 

 tively high leaf module, with canes which might be thick oi' thin but with a 

 leaning towards the thin side, rather long but not very, and with a moderately 

 high cane module. Where the seedlings are the result of a definite cross 

 between two different species of Saccharum, these rules do not hold good- In 

 fact, we should, according to the tables, look in these crosse ; for higher sucrose 

 in thicker canes with broader leaves, but the results with the other factors are 

 not clear and ars contradictory among themselves, ajid \v(> need more cases 

 before any definite conclusions can be arrived, at. Jt is j)robable that the 

 tendencies will depend on the peculiarities of the parents in each separate 

 case. The Nannal seedlings are an enigma, generally behaving as if they wore 

 the result of a cross, and it may be that, in these correlatioii studies, we may 

 find a means of detecting whether any batch of seedlings is a general collection 

 largely selfed or a set of crossed seedlings. 



The leaf width being very easily measured, and having given good results 

 thus far, it has been thought worth while to com])are it with certain other 

 characters, namely, thickness of stem, total weight of seedling at cro]) time and 

 tillering power, the latter two bearing inde])endently on the vigour of the cane. 



