164 
Physiologie. 
nerves of invertebrates 1 — 10 mm. per sec., in sensitive plants 
1 — 14 mm. per sec., in ordinary plants 3—50 mm. per sec. Vibro- 
vascular elements, the paths of longitudinal conduction, action of 
drugs the same as on nerves. 
Conductivity: the conductivity balance, effect of temperature and 
fatigue on conduction. 
Electrotonus; Pflüger’s law; the molecular theory of excitation; 
molecular variations. 
Sensation; memory. F. F. Blackman. 
Ewart, A. G., On the Supposed Extracellular Photosyn¬ 
thesis of Carbon Dioxide by Chlorophyll. (Proc. Roy. Soc. 
London. Ser. B. Vol. LXXX. p. 30—36. 1908.) 
This paper is an attack on the recent work of Usher and 
Priestley upon extracellular photosynthesis. 
It is stated that gelatine of all kinds gives the pink ‘aldehyde 
reaction’ when decolourised rosaniline is poured upon its surface, so 
that this appearance cannot be taken as satisfactory evidence of 
formation of formaldehyde when gelatine films coated with Chloro¬ 
phyll are exposed to sunlight. 
It is also argued that formaldehyde is formed in traces during 
the bleaching of Chlorophyll by light, even in the absence of C0 2 , 
and that therefore its occurrence cannot prove that the first stage 
of photosynthesis is taking place. 
The petals of most white flowers contain traces of Chlorophyll 
so that Usher and Priestley’s detection of traces of starch in pe¬ 
tals of Saxifraga when their surface is painted with Chlorophyll and 
they are insolated in C0 2 , is not conclusive. 
Many other points of view are here controverted and a simul- 
taneous production of formaldehyde and l^drogen peroxide is con- 
sidered chemically improbable. F. F, Blackman. 
Gerber, C., I. Action des acides homologues etdesacides 
alcools sur la caseification du lait par les presures 
vegetales. II. Pa r ticular ites de l’action de quelques 
acides bibasiques sur la caseification du lait par les 
presures vegetales et animales. (Soc. Biol. Paris. LXIV. 
p. 982. 5 juin 1908.) 
I. Les acides monobasiques homologues de la Serie grasse se 
comportent tous de la m6me faqon. Ils sont retardateurs ä faible et 
moyenne doses, accelerateurs ä forte dose, de la caseification du 
lait cru par le suc de Coronilla juncea L. ä 40°. Ils sont accelera¬ 
teurs ä toutes doses pour la coagulation du lait cru par le suc de 
Broussonetia papyrifera L. ä 55°. Les fonctions alcools s’ajoutant 
aux fonctions acides dans les acides alcools sont capables de jouer, 
dans la caseification, le röle de fonction acide supplementaire, sans, 
toutefois, etre äquivalente aux fonctions acides. 
II. Les acides mineraux, en general, sont accelerateurs ä toutes 
doses. S0 4 H 2 fait exception ä cette regle. II est accelerateur ä faible 
dose, retardateur ä dose moyenne, accelerateur ä forte dose. Les 
acides organiques bibasiques sont accelerateurs vis ä vis des pre¬ 
sures du type Broussonetia, retardateurs ä dose moyenne vis ä vis 
des presures du type Ficus. L’acide oxalique fait exception; il est 
