368 Mr. W.S. Perrin. On the Meets 
the interior of the leaf, and the production of haustoria and intercellular 
conidiophores. 
The author, reviewing the results of the investigations, points out that 
they afford proof that #. Graminis is not, as perhaps might have been 
expected, so highly specialised as an ectoparasite as to be necessarily restricted 
for its food-supply to cells of the epidermis; but shows itself capable of 
immediate adaptation to conditions closely resembling those obtaining in 
endophytism. 
This fact suggests the possibility that under some circumstances the 
mycelial hyphez of species of the Hrysiphaceew which are normally ectopara- 
sites may penetrate into the internal tissues of their host-plants exposed through 
wounds caused in nature by the attacks of animals or by physical agency 
It is pointed out, however, that the successful entry of the hyphe might be 
prevented, either by the drying up of the superficial layers of cells, or by the 
healing processes shown by many actively growing leaves. | 
A Preliminary Communication on the Infe History of 
Trypanosoma balbianu. 
By W.S. Perrin, B.A., Shuttleworth Research Student of Gonville and 
Caius College, Cambridge. 
(Communicated by A. Sedgwick, F.R.S. Received May 1,—Read June 8, 1905.) 
Trypanosoma balbianit, Certes, is a primitive member of the family of the 
Trypanosomide, and occurs in great numbers as a parasite in the gut of the 
oyster, where it may be present, either swimming freely in the fluid contents 
or enclosed within the crystalline style, when this structure is present. The 
species has been worked at by Certes* and Lustrae,f the latter of whom 
describes the presence of an undulating membrane and the external features 
of the process of division. The nucleus is, however, described by neither 
author. 
The material used in prosecuting this research was obtained from oysters 
fished from the Adriatic Sea, off the coast of Rovigno, but the parasite also 
occurs in the oysters of Schleswig-Holstein and the north coast of France. 
The distribution is thus a wide one. The research has been carried out under 
* Certes, ‘Bulletin Soc. Zool. France,’ vol. 7, 1882, p. 347 ; ebenda, vol. 16, 1891, p. 95. 
+ Lustrae, ‘ Actes d. 1. Soc. Linn. Bordeaux,’ vol. 50, 1896, p. 265. 
