
No. 425.] NOTES AND LITERATURE. 405 
would represent the weight of the fluids which leave the body on 
evaporation at this temperature. The relation 
is known as the fluid coefficient and signifies the percentage of fluids 
in a unit of weight of the living insect body. Experiment shows that 
the smaller the fluid coefficient the lower lies the normal congealing 
point of the fluids. The critical point is also influenced by the fluid 
coefficient, but this influence cannot be stated in general terms till 
the composition of the fluids has been further studied. Time also 
influences the critical point. If the temperature (7) to which the 
insect is undercooled coincides at the same rate of cooling with the 
critical point (.&,), the juices at once begin to congeal (z.e., time = a); 
but if ¢ does not coincide with Ay, the congealing of the fluids is 
delayed in proportion to this difference (A, — /). 
Undoubtedly Bachmetjew's results are of a far-reaching character 
and will ultimately form the basis for important work along theo- 
retical lines in physiology, and for practical applications of great 
moment (in economic entomology, e.g. !), for they throw light on the 
geographical and climatic distribution of organisms, the resistance of 
animals and plants to cold and heat, and the problems of anabiosis. 
That Bachmetjew himself is very sanguine concerning the results 
that may ultimately flow from his work is apparent when he says. 
“ Es eröffnet sich somit ein ganz neues Gebiet für die Forscher, und 
wer weiss, ob die Zeit nicht nahe ist, wo man den màrchenhaften 
hundertjáhrigen Schlaf auch bei Menschen künstlich hervorrufen 
könnte! Die Insekten wenigstens bieten die Möglichkeit dazu.” 
. W. M. W. 
An Important Paper on Phoride.— Theodor Becker, of Liegnitz, 
Prussia, has recently published a work! of roo pages, with five 
plates, on the family Phoridz, which deserves notice among zoolo- 
gists in general because it is one of the finest pieces of systematic 
work that has been published on the Diptera. 
The family Phoridz includes only small species, generally from 
two to four millimeters in length, which do not offer to the observer 
with a hand lens a satisfactory series of specific characters. The 
genus Phora was early described and generally recognized: from its 
1 Abhandlungen der k. k. zool-botan. Gesellschaft in Wien, Bd. i, Heft 1, 1901. 
