MUTATIONS, VARIATIONS, AND RELATIONSHIPS OF THE OENOTHERAS. 75 



GENERAL DISCUSSION. 



HISTORICAL CONSIDERATIONS. 



With the increasing attention being enhsted in the subject of mutations in 

 organisms, numerous records of the sahatory activation and latency of char- 

 acters in hues of descent are being disclosed by workers in all branches of bio- 

 logical science. Some observations published by Dr. Arthur HoUick in March, 

 1879 (Hollick, 1879) are among the most suggestive. The views expressed by 

 Dr. Hollick over 26 years ago harmonize so well with the sum of informa- 

 tion available at the present time that it will be profitable to give them in 

 full in this place. He says: 



The object is more to call attention to a few facts which seem to have been generally 

 passed over in botanical researches as devoid of interest. The whole subject arranges 

 itself under two heads. The first will comprise true "albinos" or such plants as have 

 spontaneously, in a state of nature, lost their colors and become white flowered. The second 

 relates to those plants in which the colors have been more or less eliminated by artificial 

 means. 



First, then, we have to consider those "sports" of nature where there has been a sudden 

 change, without any intermediate steps, from a plant with colored flowers to a pure white 

 variety; which change, for want of a better term, we may call "spontaneous. " Such may be 

 aptly termed "negative" varieties, since their pecularity is due rather to an absence of their 

 normal color than to the presence of white. 



It is nothing uncommon to see, in many species, a gradual change from a brightly colored 

 individual, through successive lighter and lighter ones, until a pure white is reached. This 

 may be very well seen in Hepatica triloba, which comprises individuals of every shade from 

 dark purple to white; or in Polygala sangiiinea, in which v.e find the same gradual change 

 from a dark red. * * * 



The following list of "albinos" is made from specimens collected during the last three 

 years. Vernonia novaboracensis Willd., Lappa officinalis var. major, Lobelia syphilitica 

 Linn., Epiphegus virginiana, Verbena hastata Linn , Asclepias incarnata Linn., Trijolium 

 pratense Linn., and Brunella vulgaris Linn. Both Gentiana crinita Froel. and Lobelia 

 cardinalis Linn, have been reported to me as having produced at times albino forms, but I 

 have never seen them personally. * * * 



Now, in the first place, not only does the flower show the characteristic absence of color 

 but the leaves, stem, and, in fact, the entire plant, are invariably of a lighter green; and if 

 any red or green should be normal to the stem (which is often the case) this will also be of a 

 lighter shade. * * * 



Secondly, if we have under consideration a plant which commonly is known to have 

 juice of an acid or peculiar taste, this is generally more or less absent in the albino form, and 

 sometimes is eliminated entirely. Darwin has noted this fact, and, in commenting upon it, 

 says that honey bees evidently are aware of it, for they perforate the calyx and corolla of 

 the white Aconitum napellus, to get at the nectaries, but will not so do with the colored 

 ones. * * * 



It has often been urged that these albinos are mere "sports" of Nature, with nothing 

 constant about them; their peculiarities due, often, to growing in the shade, etc. In fact, 

 that it is a condition due to bleaching or insufiicient sunlight, and that there is nothing 



