( 1077 ) 
The oxidation of quercite to pyrogallol is caused only by certain 
varieties of Pseudomonas aromatica, so that we have here a very 
specialised function. Green-malt extract allowed to grow “aromatic” 
by spontaneous corruption at low temperature abounds in that species 
and always contains numerous quercite bacteria which besides, are fairly 
common in sewage and even in canal water as also in “aromatic milk”. 
Melanine formation from tyrosine is proper to certain sea-vibrios 
and to Meierospira tyrosinatica not uncommon in sewage water and 
easily found by this reaction. It is a microbe closely allied to the 
cholera and the photogenic vibrios. The tyrosinase function is some- 
times suddenly lost by unknown influences, but may return in the 
same stock. Notwithstanding, the species can be considered as fairly 
constant and remains so for years in the laboratory. 
Beer, poor in extract, colours dark brown when corrupting at the 
air. This is owing to the presence of a vinegar bacterium, Aceto- 
hacter inelanogenum, which produces a pigment reminding of caramel 
from peptone. By the secretion products of A. melanogenum gelatin 
is as it were tanned and becomes insoluble in boiling water. Perhaps 
chinon is inferred in this process. 
In natural varieties of the species of microbes, which in all other 
respects show no difference, the oxidation function in regard to certain 
substances may be either or not present, but if present it may be 
very constant in these varieties. 
Zoology. “The Kutherian and the Metatherian early blastocyst’. 
By Prof. A. A. W. Husrecur. 
The careful description of the early development of the Marsupialia 
by Prof eden Hin sin, vol. 56, ptc, of the Qi. of mer: Sers has 
been anxiously awaited by numerous vertebrate embryologists, who, 
being acquainted with Hin1’s important contributions (together with 
Witson) to the ontogeny of Monotremes, expected that a firm basis 
would henceforth be established on which the mutual relationships 
of the more primitive and the more specialised Mammalia might be 
built up. Im this respect however the valuable publication, above 
referred to, is a deception. Far from being exhaustive it presents 
the limited number of observations available in the light of an inter- 
pretation in which the distinction of what is normal from what is 
abnormal, is largely dependent on numerical relations and in which 
the representatives of the so-called abnormal blastocysts are not fully 
introduced to the reader, nor sufliciently described at leneth, to enable 
the interested student to form an opinion for himself. 
