76 



LECTURE VI. 



arisen by millions of small cells (i.e. spores) having become loosened from the 



Fungus, and fallen on to the paper beneath. 



In the first place, then, and espe- 

 cially when we investigate anatomi- 

 cally the more highly developed 

 plants, the cells appear as chambers, 

 or as a framework in the substance of 

 the plant. We see, however, that these 

 chambers may also become separated 

 in part or wholly from one another, so 

 that they finally appear as independent 

 bodies. In many Algae and Fungi, 

 (e.g. the Yeast fungus) indeed, all 

 the cells arising during growth be- 

 come separated from one another. 

 Finally I may again refer to the 

 non-cellular plants or Cceloblastm. 

 We have found examples of these 

 already in the genera Caulerpa, 

 Botrydium, and Vaucheria, and have 

 seen that their substance is not 

 divided up into cell-chambers. But 

 every such plant arises primarily by 

 the growth of an isolated cell, which 

 may assume the most various forms 

 later on. A fully grown plant of this 

 kind may thus, in a certain sense, be 

 considered as a single cell; on the 

 other hand, however, it appears in 

 comparison with ordinary plants as 

 a non-cellular plant, because in it 

 the formation of chambers during 

 growth, on which the cellular struc- 

 ture depends, is suppressed. 



It follows from what has already 

 been said, and will become still more 

 evident subsequently, that we must 

 not imagine the cellular structure of 

 a plant to be due to cells previously 

 .independent becoming united with 

 one another to form an aggregate; 

 but we must regard the cells as 

 small portions of the growing plant- 

 substance, which either remain united 

 to one another, as is usually the case, 



or eventually become separated from one another. According as we keep the 



FIG. 73,— Portion of a transverse section through the testa of the 

 seed of a Gourd. 



Fig. 74. — Ripe pollen grain of Cichoriian Intybits, The almost 

 globular cell-membrane is beset with ridges connected in a net>like 

 manner, each of which bears pectinate series of spines. 



