182 Dr. H. Charlton Bastian on Diatoms and the 
and then, when diatoms are present, they are also of various 
SIZes. 
5. Old, partially empty, spaces are often to be seen con- 
taining the Chlorochytrium iission-products, small or large; 
others may be found containing diatoms, small or large; and 
others again partially empty, but containing a mixture of the 
algoid fission-products with diatoms of a corresponding size. 
6. Other spaces still densely filled will show, with the 
algoid cells, diatoms either packed in their midst or occupying 
the boundaries of the spaces, and often differing greatly in 
size in the two situations. They are likewise to be found 
occasionally in the narrow spaces between contiguous 
spherical cells, where, as I have said, algoid spores from the 
parent brood not unfrequently penetrate. 
7. In the spaces where the algoid cells and the diatoms are 
mixed some of the cells may be seen to have assumed the 
brownish-yellow colour of the diatoms, and some of such cells 
may also be seen more or less elongated and apparently deve- 
loping into diatoms. 
8. The majority of the diatoms have an immature appear- 
ance. ‘Ihe siliceous envelope in the great majority of them 
seems to be either absent or very imperfectly developed, and 
unmistakable evidence that multiplication of these immature 
diatoms has taken place is frequently to be seen”. 
There is no probability, and no one, I think, is likely to 
maintain, that diatoms are normal phases in the life-history 
of this parasitic alga; and as a careful consideration of the 
evidence as a whole appears utterly irreconcilable with the 
infection hypothesis, we seem unavoidably driven to the con- 
clusion, which is so congruous with all the facts, that the 
diatoms in question are heterogenetic products actually pro- 
duced by the transformation of the cells of the alga, alike in 
the substomatal spaces and in the epidermal cells. 
I include the epidermal cells in this statement, because 
* Some of the differences in size, apart from differences in the size of 
the algoid fission-products from which the diatoms have originated, may 
be due to increase in bulk of these immature organisms. Although this 
is at variance with commonly received views, it is in accord with the 
observations of George Murray, who says (Joe. cit. p. 216) that young 
diatoms formed within a parent by a process of rejuvenescence when 
liberated by “the separation of the parent valves at the girdle may grow, 
divide, and multiply before fully attaining the characteristic external 
sculpturing and adornment of the parent.” Young diatoms originating 
in fresh water may find silica in all pond-water. The ammonia con- 
tained in main-water, like other alkalies, easily dissolves silica or 
aluminium silicate when in a finely pulverised state, and one or other 
of these compounds is to be found in all soils (see Prof. Edwards, “ On 
the Solubility of Silica,” ‘The Chemical News,’ Jan, 1896, p. 13). 
