1883.] 



AND HORTICULTURIST. 



183 



coincident with the skill of the operator and the 

 means of performance. But I find that Caladium 

 pollen has not the least effect on the flowers of 

 Dieffenbachia ; that, after having experimented 

 for two seasons on at least two dozen flowers, I 

 could not detect the faintest trace of fertility. 



The experiment is another of the series men- 

 tioned above. It extended over the same period 

 of time, was carried on simultaneously, and under 

 the same conditions. With the same pollen I suc- 

 cessfully crossed, reciprocally, the Caladiums 

 without a single failure ; but in attempting to cross 

 the Dieffenbachias with Caladium pollen the re- 

 sult has ended in total failure. On the same plants 

 where this failure occurred I successfully crossed, 

 reciprocally, the Dieffenbachias. But to this sub- 

 ject I shall return in a future number, as I have 

 collected a mass of facts which I cannot utilize at 

 present. 



One puzzling incident in connection with this 

 matter I may mention here, as affording a strong 

 contrast to the effect, or rather the non-effect, of 

 the Caladium pollen. I dusted one of the flowers 

 of Dieffenbachia picta with pollen taken from 

 Anthurium crystallinum, which happened to 

 come in bloom at the time. The effect of this was 

 curious ; in less than three hours the parts of the 

 flower so dusted turned black, and in the course 

 of three or four days shrivelled and dried up. Was 

 this a sign of incipient fertilization ? The flowers 

 of Dieffenbachia usually remain fresh and plump 

 for two or three weeks after being prepared for 

 hybridizing. 



THE MOTION OF ROOTS. 



BY PROF. W. J. BEAL. 



It has long been known that many parts of 

 plants possessed the power of spontaneous motion 

 to a greater or less extent. The late Charles Dar- 

 win made some very interesting experiments on 

 this subject. During the past two years I have also 

 made a great many experiments on this subject. 



Roots, stems, and leaves bend to all points o< 

 the compass successively with a sort of rolling 

 motion, which Darwin calls circumnutation — a 

 bowing around. Roots grown in damp air in the 

 dark will often make a complete coil, and some- 

 times two or three of them. If a piece of gummed 

 paper be placed on one side of the root tip it be- 

 comes unusually excited and begins to coil away 

 from the paper, sometimes tying itself into a knot, 

 and often succeeds in rubbing off the paper. 



The root generally turns downwards, no matter 

 in what direction it first protrudes from the seed. 



This is not always true, however, in all of the de- 

 tails. In sprouting 400 or more kernels of Indian 

 corn in damp air, I found the direction taken by 

 the root to vary. 



During the past summer I tested some 700 ker- 

 nels of Indian corn in loose soil ; some in the cel- 

 lar, some in the garden. In damp air roots fre- 

 quently came to the surface of the soil, where they 

 apparently grew just as well as they grew be^ow 

 the surface. In the garden, exposed to the sun, it 

 is not unusual for roots of corn and beans to come 

 to the surface and perish. 



I planted some Lima beans with the eye edge up- 

 permost. Many of them came up after a fashion, 

 but they were, a good deal confused. They bent 

 around in various directions, and were very inter- 

 esting to study. 



In the garden nine out of twenty-five, over one- 

 third, of the Lima beans planted with the eye up- 

 permost, sent the radical with all the roots out of 

 the ground, when the whole bean perished. 



Darwin made a large number of experiments on 

 a great variety of seedling plants, including some 

 trees, and all, without exception, showed motion 

 of the roots, stems and leaves. He placed a young 

 root under a compound microscope, where he 

 could see it move. He sprouted some beans and 

 placed the tips of the roots against a smoked 

 glass to see what kind of tracks they would make. 

 The tips, in their downward course, had alternately 

 pressed with greater or less force on the plates, 

 and had sometimes nearly left them. 



As soon as the tip of the radicle protrudes from 

 the seed-coats, it begins to circumnutate, and the 

 whole growing part continues to do so, probably 

 as long as growth continues. When the earth 

 closely surrounds the roots they may, perhaps, be 

 quite prevented from circumnutating. The ten- 

 ; dency to circumnutate must aid in finding the 

 places of least resistance in the soil. Geotropism 

 does not give a root force sufficient to penetrate 

 the ground, but merely tells it which coarse to 

 pursue. The strength of the radicle of a bean is 

 not enough to indentate the thinnest tin foil when 

 placed horizontally with the radicle thrust perpen- 

 dicularly downwards. The .radicle in such cases 

 turns to one side and glides over the tin-foil with- 

 out makmg any impression. The growing part 

 does not act like a nail driven into a board, but 

 more like a wedge of wood driven slowly into a 

 crevice. 



[This is part of an address before the Michigan 

 State Horticultural Society in December last. — 

 Ed. G. M.l 



