HORTICULTURE. 471 



HORTICULTURE. 



The relation between hybrid characters and those of their parents, H. 



De Vries (7i'(7-. (ii'n. Bill., 7.7 ( 1903), No. 174, pp- 241--o2). — The laws governing the 

 production of hybrids are stated by the author as follows: (1 ) Crosses between forms 

 corresponding to elementary or progressive species give constant hybrids. Some 

 common examples are ^-Egilnps Kpelt.Tformis {^E. ovaia X Triiicum vulgare) and Medl- 

 cago media (M. faleaUi X sativa). (2) Crosses between forms corresponding to prop- 

 erly called varieties, retrogressive or "degressive," give hy1)rids whose offspring 

 separate according to the law discovered by ilendel for peas. (8) When the differ- 

 ence between the 2 jiarents of a hybrid is in part of a progressive nature and for 

 the other characters of a retrogressive or "degressive" nature, the offspring of the 

 hybrid does not change for the first, but separates ai'ccirding to the latter. 



The author states that the first 2 cases are simple, Init relativel}' rare. The 

 third is the ordinary (>ase for the large majority of crosses made l)y different investi- 

 gators. A number of examples are cited under the different laws. 



As explanatory of the words "progressive" and "retrogressive," the author notes 

 that when new characters are being acquired by an individual this constitutes a 

 "progressive" mutation. Once acquired, however, a character may not always 

 remain visible in the development of an individual. AVhile not apparent it may be 

 present in a latent state. This the author calls a "retrogressive" mutation. 



The forward movement in plant breeding, L 11. Bailey {Pror. Atiter. Phil. 

 Soc, 4^ {1903), No. 172, jjj). 54-G8). — This is a comprehensive review of the work in 

 plant breeding now being carried on in America. It deals with the methods, ideals 

 sought for, and results obtained. Tlie woi-k with corn in Illinois and wheat in 

 Minnesota is noted in considerable detail. 



Forcing rhubarb in the dark, V. 11. Davis [Jonr. C'ohunJniR Hort. Soc, h9 

 {1903), No. 3, pp. 86-01, fiy a. 3). — The details and results secured in winter forcing 

 seedling rhubarb roots are recorded. Usually only crowns from 3 to 5 years old are 

 used for winter forcing. In the present experiment seedlings obtained l)y sowing 

 seed in April in drills 2-1 in. ajiart were used. The seedlings made a remarkably good 

 growth during the sunnner, many leaves attaining a foot across, with stalks ir> to 20 

 in. long and an inch thick. 



After the ground had been frozen and thawed out once in the fall the roots were 

 plowed out and placed in a dark cellar. They were packed closely together, with 

 the crowns up and soil sifted between until the roots were covered 2 or 3 in. deep. 

 They were then thoroughly soaked with water and the room made perfectly dark. 

 The stalks pushed rapidly into growth and within 4 weeks an excellent growth of 

 rhubarb was secured. These seedling roots furnished 2 pullings of first-class stalks, 

 2 more of fair stalks, and 2 or 3 more small pullings of rather small and spindly 

 stalks. 



In all, the one crop lasted about 4 weeks. The exhausted roots were then removed 

 and a new supply grown in like manner. It is stated that in this work the tempera- 

 ture should never be allowed to go above 60° F., unless quick results are wanted at 

 the expense of quality and quantity. The crop grown in this experiment sold for 

 from 60 to 75 cts. per dozen bunches, and there were from 4 to 6 stalks in each bunch. 

 From an area of 370 scj. ft. of cellar space rhubarb to the amount of $35.55 was sold, 

 and it is believed that the yield obtained in this experiment can be materially 

 increased when more attention is given to the growing of the seedlings. 



Special mention is made of the desirability of growing the roots in absolute dark- 

 ness, since by this method the strength of the root is directed into the stem of the 

 rhubarb rather than into the production of foliage. "By i)lanting the seed on 



