Reproduction of Cyst op us Candidas , Ldv. 315 
nigrosin stain ; where it is very dense, however, the red stain 
predominates. The haustoria are small, spherical projections 
produced here and there on the hyphae, occasionally in con- 
siderable numbers. They often indicate the presence of the 
mycelium before this has been observed, and it is often very 
difficult to see their connexion with the hyphae upon which 
they are borne owing to the small size of the connecting tube. 
The protoplasm in the haustoria takes always a distinctly 
blue colouration in the carmine-nigrosin stain, with no tinge 
of red. In some cases it is very dense, stains deeply, and 
nearly completely fills the cavity; in others it forms a peri- 
pheral layer of deeply stained granules around a central 
vacuole. I have never been able to observe nuclei in the 
haustoria, although Dangeard (TO) states that they sometimes 
contain one. This is perhaps interesting from the point of 
view of the function of the nucleus, as showing that the 
presence of a nucleus in the haustoria is not absolutely 
necessary in order to enable them to properly perform their 
function of absorption of food-material. It must be pointed 
out, however, that as these haustoria always remain small, 
and that the whole of their protoplasm therefore is not far 
removed from the influence of the nuclei of the hyphae upon 
which they are formed, there may be no necessity for the 
actual presence of a nucleus in them. In P. parasitica, where 
the haustoria are very large and sometimes nearly completely 
fill the cells of the host-plant, they always contain numerous 
nuclei. The protoplasm of the haustoria in these stained 
sections is generally shown slightly contracted away from the 
wall equally all round, which gives them a very characteristic 
appearance, as if they possessed a very thick cell-wall. 
The nuclei of the mycelium are generally very loosely 
arranged in the protoplasm, but where the protoplasm is 
abundant and where probably active growth is taking place, 
the nuclei are more numerous. In the former case the 
structure of the nuclei can be easily observed, but not in the 
latter. In the resting condition each nucleus consists of 
a nuclear membrane, network, and nucleolus. The network 
