April 17, 1895.] 



Garden and Forest. 



155 



beauty of the flower lies in the stamens, of which there are 

 something- like forty in each one of the twenty flowers 

 which make up a single head. The plant thrives equally 

 well in the temperate house or stove, but when grown in 

 the latter it flowers from two to four weeks earlier. The 

 flowers appear with the new foliage, and the contrast be- 

 tween the two is very pleasing. Every summer the plant 

 should be encouraged to make as much growth as possi- 

 ble, as the flowers are always produced on the previous 

 summer's wood and are grown on peduncles an inch and 

 a half long. The shrub grows to a height of about five 

 feet. 



Brunfelsia (Franciscea) latifolia. — Brunfelsias are ever- 

 green shrubs, mostly from Brazil, and many of them have 



Fii^. 24. — Echinocactus Wislizeni, var., j^rowinx in Ihe FMOlhills ol llie Sanla Cat 

 Mountains, Arizona.— See pa^e 154. 



been long in cultivation. They need a warm house with- 

 out too much sun, and, although they will take abundant 

 water when growing actively, the ground should never be 

 sodden, or the roots will suffer, and it is a long process to 

 restore the plant to health. B. latifolia takes rank among 

 very choice stove-shrubs, and healthy plants will be cer- 

 tain to bloom in profusion every spring. The flowers are 

 an inch and a half in diameter, of a dark lavender color as 

 they open, and they change to pure white. When planted 

 in coarse peaty soil with good drainage they need no 

 special care beyond a severe cutting back as they become 

 established, in order to keep them compact — that is, to pre- 

 vent them from growing into a straggling form. 



Cultural Department. 

 A Test for the Quality of Potatoes. 



EVERY one knows how much more palatable some 

 potatoes are than others, and there is quite as marked 

 a difference in their food value as estimated by the amount 

 of nutriment they contain in the form of starch. Professor 

 Goff, of the Wisconsin Experiment Station, has been mak- 

 ing some tests with potatoes which are novel and sugges- 

 tive, and they point the way to a line of investigation 

 which it may be worth while to follow out with careful 

 study. We reproduce, in a somewhat condensed form, 

 Professor Goff's account of his experiments in the Rural 

 Neiv Yorker : 



In making brine for beef it is an old custom to put 

 a potato in water and stir in salt until the potato 



1 Hoats, and this usually proved a safe test. But if 



two or more potatoes are put in at the same time, 

 they will rarely come up at once. Even when the 

 potatoes are all of the same variety, and are taken 

 iromthe same bin, considerable more salt is required 

 to bring up some tubers than others. This means that 

 sometubers have a higher specific gravity than others. 

 Now, starch, the portion of the potato that makes it 

 chiefly valuable for food, is heavier than water ; hence 

 the heaviest potatoes contain the most starch, and so 

 have the highest food value. They are also finest 

 for table use, because they have the most farinaceous 

 or mealy quality when cooked. 



Here is a pointer for potato epicures. By putting 

 a bushel of potatoes into a barrel which is nearly full 

 of water, and stirring in salt, the tubers of the lowest 

 specific gravity — that is, those poorest in starch — will 

 first come to the top. These may be picked off. By 

 stirring in a little more salt another lot will rise, and 

 thus the bushel may be assorted into several quali- 

 ties. By rinsing the tubers in clean water as they are 

 taken out, they are uninjured, either for table use or 

 for planting, and it is surprising to one who has not 

 made the test, to discover how great is the difference 

 in the table quality of the lightest and heaviest tubers. 

 ' Tlie former will be soggy and salvy, while the latter 



will be Haky and farinaceous. 



On discovering this marked difference in the qual- 

 ity of individual tubers of the same variety, the ques- 

 tion naturally arose as to its cause. It has olten been 

 stated that pronged or knobby tubers are poorer in 

 starch than others. The salt test easily shows this 

 to be true. But some smooth tubers will usually 

 rise as soon as the knobby ones, and it is an inter- 

 esting fact that these light smooth tubers are often 

 undistinguishable by any external mark from the 

 heaviest ones, and this is true even of tubers that 

 grew in the same hill. 



Some years since I set out to discover the cause of 

 this singular variation in the starch content ot differ- 

 ent tubers. The first suggestion was that it might be 

 due to heredity. Accordingly, a lot of potatoes was 

 assorted into three classes by the salt method, and the 

 tubers showing the highest and lowest specific gravity 

 planted separately. But no appreciable difference 

 appeared in the specific gravity of the crops. The 

 same line of selection followed another year showed 

 _ no more definite results. The question next arose, 



whether the variation might not be due to the vary- 

 !ma '"g depths at which the tubers grew in the soil, and 



this appeared to be the true solution. Careful tests 

 with several different varieties, and with different 

 methods of culture, carried on through two consecutive sea- 

 sons, showed that the tubers that grew nearest the surface of 

 the soil were lowest in specific gravity ; those that grew deep- 

 est were highest, and those that grew in the intermediate depth 

 were intermediate iif^specific gravity. This fact suggested that 

 the temperature of the soil in which the tubers grow, may have 

 an influence upon their specific gravity, and that a compara- 

 tively cool temperature favors high specific gravity. In sup- 

 port of this view, it may be added that potatoes grown in level 

 culture averaged higher in specific gravity than those hilled, 

 and tests have shown that level soil usually averages lower in 

 summer temperature than that which is ridged. 



Potatoes grown closely in drills were found higher in specific 

 gravity than those grown farther apart in hills — the more 

 largely shaded soil of the drill culture being thereby rcifdered 



