The Mickoscope. 131 



quite regular rows, occupying the cells of a thin, hyaline, cellular 

 membrane (Fig. 5, b), and irresistably remind one, by their color 

 and arrangement, of a brick pavement. The membrane is seated 

 directly upon the cells of the cotyledon, and the partition walls of 

 its cells are thickened and beaded. (Fig. 5, c.) A higher magnifi- 

 cation shows that the edges of the red blocks are finely serrate (Fig. 

 5, c), and the partition walls of their investing cells correspondingly 

 notched to fit them. (Fig. 5, d. ) It seems obvious that these red 

 blocks are the solidified contents of the cells they occupy, and that 

 they are in fact overlaid by an outer cell-wall, but I have been una- 

 ble, even with a great number of specimens, to demonstrate its 

 existence. 



The seeds, when placed in water for a few hours, yield an 

 abundant colorless mucilage, by which a moderate quantity of water is 

 emulsified to a jelly. That this is mostly yielded by the testa, is seen 

 by a section of the soaked seed after boiling it in a fresh quantity 

 of water. The cotyledon is but slightly changed, but the coats of 

 the testa are swollen and separated by a clear space, the outer cells 

 ruptured (Fig. 6), the oil-drops occupy less of the now enlarged 

 cotyledon- cells, and the latter, where the oil-drops have escaped, dis- 

 charge a cloud ,of minute starch particles. (Fig. 6 a.) The ele- 

 ments of the husk or testa are, however, still indistinct in the swol- 

 len section, but the cotyledons of the boiled seeds are readily 

 squeezed from the testa, leaving the same in a condition to be easily 

 teased out and examined. Heating a few of the dry seeds in nitric 

 acid causes them to lose their color and soften, and the outer coat of 

 the husk comes away as a white film, leaving the inner coat and 

 cotyledon pale yellowish, soft and easily crushed to pieces. By 

 examining in water or glycerine the teased-out coatings of the testa 

 and fragments of the cotyledon obtained by these methods, a satis- 

 factory determination of the structural elements is arrived at. First, 

 however, a section of the dry seed is treated with water, when the 

 outer cells of the testa instantly swell up, their partition walls pre- 

 senting a wrinkled appearance (Fig. 7, a), and the whole substance 

 of the outer coat slowly thickens and swells, which action is hastened 

 by the application of potash solution. By treating the section with 

 successive quantities of potash, or of ether or chloroform, the oil 

 globules diminish and finally disappear, presenting successively the 

 appearances shown in Fig. 7, b, c, d, e. 



The structure of the outer coat of the testa, as revealed by the 

 teased-out specimens, is shown in Fig. 8, which represents, diagram- 



