REVIEWS. 
355 
"by the system of 1 discontinuous boiling ’ adopted by the author in the case 
of certain exceedingly 1 obdurate germs/ such as the spores of the hay bacillus, 
which, ‘ when thoroughly desiccated by age, have withstood the ordeal ’ of 
boiling for eight hours. Prof. Tyndall assumed that these desiccated germs 
resist the effects of heat by reason of their desiccated condition, and that 
before developing a crop of Bacteria in any infusion, they must necessarily 
pass into a soft and plastic state. Accordingly having set aside an infusion, 
undoubtedly infected by some of the most resistant germs, for ten or twelve 
hours, he then raised its temperature to the boiling point, and set it aside 
once more. By a repetition of this process the germs as they successively 
advanced towards the stage of active development, were caught and destroyed 
by the boiling temperature ' in the order of their resistance ’ — in fact, the 
Professor effected a sort of fractional destruction of them, and by repeating 
the process a sufficient number of times his infusions were all completely 
disinfected. ( Not one of them/ he says, ( bore the ordeal ; ’ and the sum of 
the exposures to a boiling temperature did not exceed a few minutes. 
We shall not follow Prof. Tyndall into the discussion of what is the most 
important outcome of these researches into the nature of the atmospheric 
dust, namely, the germ-theory of disease, to which he naturally devotes a 
good deal of space in this volume ; by many medical men the matter is 
regarded as settled, and the rest of the profession will probably soon adopt 
the new faith. Upon all the leading points connected with it the reader 
will find in this volume an excellent summary of information, besides the 
details of experimental investigations, to which we have already alluded; 
and although some of the papers are communicated to the Boyal Society, 
the unlearned reader need not on that account dread, being unable to under- 
stand them. 
BRITISH MARINE MAMMALS* 
M R. SOUTHWELL has published a popular account of the Marine 
Mammalia which have been found in the British Seas, and, although 
it contains nothing particularly novel, it will serve to furnish general readers 
with accurate information, pleasantly communicated, upon a subject of which 
general readers are commonly profoundly ignorant. Mr. Southwell care- 
fully avoids any display of scientific phraseology, but he describes the 
general characters of the animals referred to with sufficient exactitude to 
give his readers a good notion of their appearance, especially in conjunction 
with the woodcut figures which accompany the notices, and which are 
generally very fairly executed. The information as to the habits and distri- 
bution of the species seems to have been carefully got together and from 
recent sources, and altogether we can recommend Mr. Southwell’s book as a 
very satisfactory contribution to the Popular Natural History of these 
Islands. 
* The Seals and Whales of the British Seas. By Thomas Southwell, F.Z.S. 
Sm. 4to. London: Jarrold & Sons, 1881. 
