THE DEVELOPMENT OF ORGANISMS 



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the life-histories of plants in a very remarkable way. This was 

 mainly due to the genius of Wilhelm Hofmeister (1824-1877), who 

 laid the foundations of his comparative embryology in the spare 

 time of his everyday work as a music-seller. What he added after 

 he became a Professor was merely extension and corroboration. 



Fertilisation and Early Development in Flowering Plants. I. Section of ovule; 

 ST, stalk; N, nucleus of embryo-sac (ES), with four chromosomes (CHR); 

 M, micropyle, through which there enters a pollen-tube (PT), containing 

 the generative nucleus (GN). II. The embryo-sac (ES) further enlarged, 

 with the nucleus divided into two (N and Ni). III. Each nucleus divides 

 into four (AC and EA) . IV . From each quartette a nucleus passes to the 

 centre, and the two fuse to form the endosperm nucleus F, leaving three 

 antipodal cells (AC) at one pole, and at the other the ovum (OV) and 

 two synergid-cells (S). V. The fertilised ovum begins to segment and 

 forms an embryo (EMB) on its stalk (ST); EN, endosperm; A, B, C, the 

 division of the nucleus of the pollen grain to form a generative nucleus 

 (GN) and a tube-nucleus (TN). The generative nucleus again divides. 



"The results", Sachs says, "of the investigations published in the 

 V ergleichende Untersuchungen, in 1849 ^^^ 1S51, were magnificent 

 beyond all that has been achieved before or since in the domain of 

 descriptive botany. . . . Alternation of generations, lately shown 

 to exist, though in quite different forms, in the Animal Kingdom, 

 was proved to be the highest law of development, and to reign 

 according to a simple scheme throughout a long series of different 



