CHYTRIDIINEAE 77 



Curtis explains short flagella such as those in Fig. 18, F, 

 as being due to immaturity. 



Entry into the host-cell is similar to that of the zygote, 

 Fig. 22, b. Having entered, the parasite first approaches, 

 Fig. 20, fr, then sinks below the host-nucleus as at c. 

 Growing rapidly the nucleolus discharges chromatic material 

 at intervals into the nuclear cavity and some of it enters 

 the cytoplasm. The chief features of what has been recorded 

 of the synchytrian nucleus is given in the next Chapter. 



Referring again to Fig. 19, D, and A 7 , we note that the 

 parasite seems to be able to excite just such cell-divisions 

 in the host-tissue as serve its changing needs. Only actively 

 dividing regions of the host-plant are attacked. At B in 

 Fig. 19 the lateral cells project to form a cup ; this serves 

 to catch rain for the hatching of zoospores shown at F. 

 At D host-cells deep to the parasite are in mitosis causing 

 a tension towards the surface where the summer sporanges 

 are to be formed : at N the surface cells are dividing, placing 

 the winter sporange deeper in the tissue of the host to 

 mature thus protected. 



