THE GENERAL STRUCTURE OF PLANTS 11 



important seaweeds and by a large number of fungi, as well 

 as by particular parts of some of the flowering plants, we 

 have a number of protoplasts arranged together over the 

 inner surface of a common cell-wall. The separate proto- 

 plasts are often in such close contact 

 with each other that their several 

 outlines cannot be detected. They 

 have the appearance of a mass of 

 protoplasm lining the wall of a 

 hollow, generally tubular, cavity, 

 and having a large number of nuclei 

 embedded in the mass. The pre- 

 sence of a number of nuclei indicates 

 that there are really as many pro- 

 toplasts, as we have seen a nucleus 

 is an essential part of one of the 

 latter. Moreover, a single proto- 

 plast contains only a single nucleus. 



The difference between a colony 

 of this kind and one constructed 

 like Chroococcus or Volvox is the 

 absence of a cell-wall between the 

 protoplasts. They are a stage 

 higher than the Myxomycetes, as 

 the whole colony is protected by an 

 external membrane. 



Other ccenocytes exist in which, 

 besides the limiting wall, certain 

 transverse walls exist, dividing up 

 the chamber into compartments. 

 This condition is intermediate 



between the coenocyte already described and the simple 

 colony or the multicellular plant. 



In most cases the division of the cells goes on for a con- 

 siderable time and may continue almost indefinitely, the 

 number of the constituent protoplasts becoming very great 

 and the colony proportionately large. According to the 



FIG. 12. EMBRYO OF Orobus AT 

 THE BASE OF A LONG Sus- 

 PENSOR. THE LATTER SHOWS 

 A CCENOCYTIC STRUCTURE. 

 (After Guignard.) 



