Productiveness and Degeneracy oe the Irish Potato 
ii 
Professor Alvin Keyser cites the work of Professor E. G. Mont¬ 
gomery, which affords a somewhat parallel phenomenon with Indian 
corn. About fourteen nodes are typical of the corn stalk, the upper 
seven of which are long and may develop tassels or male flowers, while 
the lower seven have power to develop female flowers and 
ears of corn. Normally one or two ears are formed and at upper 
nodes of the lower seven, but in the case of accident or removal of the 
ears naturally developing, ears may be formed at other nodes, and ex¬ 
perimentally it has been found possible to induce the development of 
ears at all of the nodes. 
The Influence of Nitrogen .—“Speaking generally, excessive food 
supply leads to infertility among both plants and animals. The former 
vegetate luxuriantly, but they do not blossom and fruit so abundantly 
as under a full but moderate supply of plant food/’ We were justified 
in making the assertion “that extreme proportions of nitrogen produce 
luxuriance in stem and leaf at the expense of flower and fruit.”* Potatoes 
need rich conditions to continue productive vegetative growth. Ex¬ 
perimentally and in commercial practice we find that seed potatoes 
grown from good stock and under good early conditions of moisture 
and health, but with only a moderate amount of plant food, on our 
buffalo sod or sage brush ground,! expand into remarkabe vegetative 
and tuber growth when planted on our rich alfalfa lands, are most near¬ 
ly asexual in habit, and have the finest tubers the first year, with usually 
the largest production the second season. 
Change of Soil .—Change from one region to another, or from 
one farm to a different but not richer soil, affords a change of food 
which is also a stimulus to potatoes and retards sexual development, 
thus maintaining to a degree good tuber shape. We find, however, 
that constant change may hold in suspension for several years the 
tendency to seed bearing and tuber degeneracy, which may then come 
suddenly, on return to less favorable conditions, or on being grown 
for a second year on the same ground. 
Identity of Tuber Parts .—Aerial tubers give the best proof of the 
morphology of tuber parts. Plate VII is a Pearl plant from which 
the tubers were removed by hand in 1910 at Del Norte. In this case 
the plant not only enlarged upper branches, many of which formed 
into tubers, but also enlarged the main stem with normal potato-tuber 
tissue. In Plate VI, page 2, note a Pearl tuber also from Del Norte 
in 1910, the result of disease. One portion of the tuber was grown 
above ground and one below. These tubers show that the eye yoke 
is the laying of the leaf onto the stem; that the yoke point is the remnant 
of the leaf stalk base; that the sprout tips are the ends of leaves later 
to be followed by the sprouts; that knots are swelled, protruding 
branches of tubers; and that “compound” eyes are but lesser knots. 
The emphasis of the yoke on aerial tubers is quite like the dif- 
* E. Davenport in Principles of Breeding, 1907, page 226. 
f To a less degree this is true of seed potatoes grown upon pea stubble. 
