1888-89.] Paton and Stockman on Metabolism of Man. 131 
While Cetti spent most of his time in a large somewhat cold room, 
Jacques, on the contrary, inhabited a small highly-heated chamber. 
In every way the conditions of his case were peculiarly favour- 
able to the maintenance of life with the smallest possible metabolism. 
Exercise was only taken in most moderate amount, while the kata- 
bolic changes necessary to maintain the temperature of the body 
were reduced to a minimum by the high temperature at which his 
room was constantly kept. 
Whether his powder had any influence in diminishing metabolism 
we are unable to say. But even without it we see no reason why a 
man should not undergo with impunity such a period of starvation 
under like favourable circumstances. 
A Method of Demonstrating the Presence of Uric Acid in 
the Contractile Vacuoles of some Lower Organisms. 
By Dr A. B. Griffiths, F.R.S. (Edin.), E.C.S. (Lond. and 
Paris), Member of the Physico-Chemical Society of St Peter s- 
burg , <hc. 
(Read January 21, 1889.) 
After some years of patient observation and research, I have 
found, from direct experiment, that at certain times the contractile 
or pulsating vacuole of the Protozoa performs the function of a true 
kidney, or, in other words, its secretion is capable of yielding micro- 
scopic crystals of uric acid. 
Three organisms were used in these experiments, namely : — 
Amoeba, Vorticella, and Paramoecium. 
I. Amceba. 
We will consider, in the first place, the small Protozoon which 
Haeckel called Amoeba sphcerococcus. By observing a number of 
these organisms under the high powers of the microscope, there is 
seen, within the structure of each, a small cavity or vacuole filled at 
certain times with a transparent fluid. There is little doubt that 
the fluid which gathers in the vacuole is drawn from the surround- 
ing protoplasmic substance, and is returned to it, or forced out to 
the exterior on the contraction of the walls of the vacuole. 
I have shown in my paper, “ Further Researches on the Physio- 
