X 



PLASSOMYXINEAE 119 



the synchytrian nucleolus appears and grows rapidly by 

 general increase : Plassomyxa appears first in the host- 

 nucleus, is next seen in the cytoplasm where it grows rapidly 

 in the nucleolar state until it is full-grown ; reproductive 

 action by the zygotic nucleolus of Synchytrium produces 

 the generative chromidium. The later changes in Synchy- 

 trium end in the production of zoospores when the ripe 

 resting-cell has been in water some days : the formation of 

 flagellate zoospores occurs also in water-culture of Plas- 

 somyxa, but the latter has alternative phases, e.g. gemmation 

 of the parasite with streaming protoplasm. The formation 

 of the capsule of the synchytrian zoosporangium is repeated 

 in Plassomyxa, definite doubly-contoured capsules being 

 frequently formed ; the formation of a supporting frame- 

 work is an alternative to this. 



The Geographical Distribution of Molluscum. The late 

 S. von Prowazek * found that the occurrence of this disease 

 was variable in the tropics. It had been met with in Samoa, 

 Brazil, Java, Sumatra, New Guinea, China, and abundantly 

 in East Africa. 



Avian Molluscum or Bird-pox 



This disease affects domestic poultry of all kinds, cage- 

 birds, and wild wood-pigeons. It so closely resembles 

 human molluscum that the question of identity arises. 



1 S. von Prowazek, one of the editors of the " Archiv fur Protistenkunde," died of 

 typhus whilst investigating that disease in 1915. 



