A TEXT-BOOK OF BOTAXV. 



Xumerous oil globules are also found in the protoplasm, and cal- 

 cium oxalate crystals may occur in the cell-sap. 



Vaucheria furnishes an example of a plant whose interior is 

 not segmented by cell-walls. In other words, the cavity within 

 the outer or enclosing membrane is continuous, and such a plant 

 is said to be coenocytic, i.e., like a syphon. But it should be borne 

 in mind that the plant contains a great many nuclei, and, as we 

 have seen (page 2), a nucleus with its associated cytoplasm 



FlG. 12. Vaucheria sfssilis. A, sporangium from which the multiciliate zoospore is 

 escaping; B. resting zoospore; C, D, germinating zoospores with growing point (s) ; E, 

 plant showing root-like organ of attachment (w), spore from which the plant is developing 



; F, sh"\ving in addition two ougonia (og) and an antheridium (h). After Sachs. 



continues a unit of work. Hence such a plant as Yaucheria is in 

 a certain sense equivalent to a plant having as many uninucleate 

 ri-lls as it lias nuclei. It would probably be better to call such a 

 plant multinucleate rather than unicellular. 



Reproduction by means of asexual spores is brought about as 

 follows ( Fig. 12, J ) : A cross wall is formed near the end of one 

 <>f the branches, the end portion constituting a sporangium. The 

 o.ntents. including numerous nuclei, group themselves into one 

 large zoospore, which escapes through an opening in the sporan- 



