234 



ISSENTUL ORGANS — THE DISK. 



contents are small utricles or cellules, varying, like pollen-grains, in the 



different orders of cryptogamic plants, 

 and enclosing peculiar bodies called 

 phytozoids (pvriv, a plant, and ^£01', 

 an animal), or spermatozoids (g-irsg/ia, 

 a seed), or antherozoids (fig. 402, 2), 

 which are rolled up in a circular or 

 spiral manner, as in Hepaticse and 

 Mosses (fig. 402, 3). These exhibit 

 active movements at certain periods 

 of their existence, and resemble in 

 this respect animalcules. In Chara 

 vulgaris (fig. 403), the antheridium 

 or globule, as it is called, contains 

 cells, 1, from which proceed numerous 

 septate (septum, a division) tubes, t. 

 ^- ^'^^ In each of the divisions of these tubes, 



2, there is a spermatozoid of a spiral form, which escapes, leaving the 

 division empty, 3, and ultimately becomes unrolled, 4, exhibiting two 

 vibratile cilia (cilium, an eyelash), to which its movements are 

 referred. 



The Disk. — The term dish is applied to whatever intervenes 

 between the stamens and the pistil, and 

 is one of those organs to which the name 

 of nectary was applied by old authors. It 

 presents great varieties of form, such as a 

 ring, scales, glands, hairs, petaloid append- 

 1^/1 ages, etc., and in the progi'ess of growth 

 / it often contains saccharine matter, thus 

 ■ becoming truly nectariferous. The disk is 

 frequently formed by degeneration or trans- 

 formation of the staminal row. It may 

 consist of processes rising from the torus, 

 alternating with the stamens, and thus re- 

 presenting an abortive whorl ; or it may 

 be opposite to the stamens, as in Crassula 

 Fig. 404. rubens (fig. 282 a). In some flowers, 



as Jatropha Ourcas, in which the stamens are not developed, their 



Fig. 403. 1, Portion of antlieridium or globule of Chara vulgaris. Several septate or 

 partitioned tubes, (, attached to a utricle or vesicle. A mass of similar utricles, forming 

 the bases of a large number of tubes, fills the cavity of the antheridium. 2, Extremity of 

 one of these tubes, composed of several cellules, in each of which is a phytozoid or sperma- 

 tozoid. One of the spermatozoids is represented half detached from the cellule. 3, Ex- 

 tremity of a tube from which the spermatozoids have escaped, with the exception of the 

 terminal cellule. 4, One of the spermatozoids separated. Fig. 404. Disk, d, of Paeonia 

 Moutan, or Tree Pseony, covering the ovary, and interposed between the whorl of stamens, 

 i, and the pistil, p. 



