5!rmu( Eu?i«^u.] Microscopic Structure of Plants. 155 



peculiar cilia with which they are provided. Lastly, we observe 

 streams of moving particles in the protoplasm of certain cells as in 

 Yallisneria and Anacharis. In general the protoplasm is granular, 

 but in the cotyledons of the Jerusalem Artichoke it seems to be 

 homogenous, and to contain very little water. In VaUisneria it 

 is very watery, and contains very few granules, while in many 

 spores the protoplasm is so loaded with colouring matter and 

 granules that no fluid basis can be detected. This diminution of 

 the fluid basis may go to such an extent that we may have the 

 protoplasm appearing in rounded granular masses with starch grains 

 lying between the masses, as in the cotyledons of the Common Pea. 



The Nucleus is frequently absent in certain Thallophytes, but 

 is present as a rule in vascular plants and mosses. The nucleus 

 generally assumes its full size at once, and in young cells seems to 

 be quite out of proportion to the rest of the cell. In young cells, 

 then, it occupies nearly the whole space of the cell, while in large 

 older cells it takes up but a very small part of the cavity. In the 

 young hairs of the Hyoscyamus niger, a further development of 

 the nucleus has been observed. A firm outer layer forms, and drops 

 of fluid accumulate in the nucleus, the granules then exhibiting a 

 regular series of movements. 



Chlorophyll being a substance always found in relation to the 

 protoplasm must be here briefly noticed. The green colouring 

 matter seems to be carried by granules of protoplasm, the proto- 

 plasmic base remaining colourless after the colouring matter is 

 removed by alcohol or ether. The granules of chlorophyll always 

 lie in relation to the protoplasm, in this resembling the nucleus, 

 and are never found free or in the cell-sap. In some cases, as in 

 zoospores, &c., the chlorophyll seems to form part of the protoplasm, 

 and is not separated in the form of granules. In Zynema we have 

 peculiarly shaped figures of green protoplasm, while in the vast 

 majority of jilants the grains are rounded. In size the granules 

 vary greatly, being very large in Selaginellas. Starch and oil are 

 also frequently found in the chlorophyll granules. 



Other bodies are also found in relation to the protoplasm, as 

 the crystalloids of Naegeli. They are portions of protoplasm which 

 assume a crystalline form, with plane surfaces and sharp angles and 

 faces. They occur in the forms of cubes, tetrahedra, octahedra, &c., 

 in various plants, are of very minute size, and the angles seem to 

 be inconstant. The crystalloids of the Potato were discovered by 

 Cohn, and are to be found in the cells of the parenchyma, under 

 the rind, which do not contain much starch. They are in general 

 cubical, and sometimes occur in large quantities. Eadlkoler dis- 

 covered them in Lathrsea squamaria. They are often in numbers 

 inside the nucleus, and their general form is that of thin square 

 plates, sometimes rhombic. Crystalloids have also been described as 



