244 RESEARCH SEMINAR. 



structure of the starch grain and that of the cell-wall was dem- 

 onstrated by micro-physical means, the use of iodine solutions 

 and aniline stains. The various types of cell-walls and modified 

 cell-walls were described as follows: (i) Cellulose walls; (2) 

 ligno -cellulose walls; (3) adipo-cellulose walls; (4) mucilage- 

 cellulose walls ; (5) pecto-cellulose walls ; (6) reserve-cellulose 

 walls. In connection with the study of the reserve-cellulose 

 walls the work of the author on the continuity of protoplasm was 

 considered, and the similarity of the structure of the walls of this 

 class to the structure of the wheat starch grain was pointed out. 

 July 2-j. History and General Factors of Plant Breeding. 



By HERBERT J. WEBBER. 



This lecture included a discussion of the history of breeding 

 from the time of Fairchild who made the first plant hybrid in 

 1719 to the present time. The principles of breeding advocated 

 by Knight and Van Mons were compared with later methods 

 and the gradual improvement traced. 



Illustrations were given of physiological variations, individual 

 or congenital variations and mutations or saltatory variations, 

 showing how the two latter forms of variations have been utilized 

 by practical breeders, while physiological variations have proven 

 valueless because not hereditary. 



The factors of breeding, including the general laws of heredity, 

 transmitting power, unity of individual isolation and selection, 

 were considered briefly. 



The speaker emphasized the importance of breeding for a 

 special purpose and with a definite idea in view. The breeder 

 should be familiar with all varieties, races, and species of the plant 

 which he proposes to improve, and select as the parent or parents 

 for his new sort, the existing variety or varieties which exhibit 

 in the greatest perfection the ideal characters which he desires 

 to combine. 



In the amelioration of a wild species it has been claimed since 

 the time of Knight that it is first necessary to " break the type " 

 as it is expressed, to get the plant into a condition of variation. 

 It is claimed that a wild plant is for some time very stable and 

 but slightly variable under conditions of cultivation, and that by 

 continuous high cultivation this stability can be broken and the 



