M. Miiller on the Get'mination of Isoetes lacustris. 325 



3. The dissolved starcli takes the appearance of oil-globules, 

 and these alone constitute the protoplasm of the first cells of the 

 embryo (fig. 6). 



4. The embryo, which is already formed at a period when no 

 alteration is to be observed in the coats of the ovule, first appears 

 as a solitary cell. 



5. It becomes a mother-cell, new daughter-cells being soon 

 formed within it. This certainly is effected through cytoblasts 

 (figs. 7, 8). 



6. Soon after this the mother-cell has become a wholly cel- 

 lular, oval corpuscule (figs. 9, 10). 



7. Hereupon, a growth toward two sides is seen at the base, 

 and the corpuscule becomes curved in» the middle, in which a 

 solitary cell displays itself : this is the rudiment of the scale of 

 the first leaf. The growth toward two sides marks the rudiments 

 of the vagina and alimentary organ (fig. 11). 



8. Two more organs are now associated with the preceding. 

 The alimentary organ becomes more evident by growing out in a 

 rounded form ; through this originates a curve on the base of the 

 embryo which is also partly caused by the root of the first leaf, 

 which is equally visible in its rudimentary condition. By this 

 also the vagina becomes directed upward, it is connected with 

 the future furrow of the leaf, and incloses, together with the 

 mother-cell of the first scale, the newly added one of the second 

 leaflet (fig. 12). 



9. The first leaf having become cylindrically elongated, it has 

 also acquired a green colour. At this time the alimentary organ, 

 root, vagina, scale and mother-cell of the second leaflet are clearly 

 distinct organs. The alimentary organ, which occupies one-half of 

 the germinal body while the other half belongs to the radicle, has 

 become filled with starch which suffices for the nutrition until 

 the second leaflet has become tolerably developed. The root is 

 still a little conical body formed of very delicate cellular tissue. 

 The vagina looks sideways, and incloses now the two mother-cells 

 of the scale and the second leaflet. The former becomes a flat 

 membrane, the latter remains a round, but internally already 

 cellular body (figs. 15, 17). 



10. The scale and root alone now visibly hasten forward in 

 their formation. The former has attained its full development, 

 while the second leaflet has only become cellular and the vagina 

 applied itself more closely upon it. The root has most visibly 

 advanced ; it has become considerably elongated and acquired 

 two vascular cords (fig. 18). 



11. The next succeeding development of all parts is merely 

 a relative expansion of them (fig. 20) . 



