0.0001 n Tart. 
150 Papers from the Department of Marine Biology. 
surface tension of water. The relation was pointed out by Traube and 
supports his theory that the more a substance lowers the surface tension 
of water, the more readily it will pass into cells. Loeb had previously 
pointed out that the more lipoid soluble acids were most efficient in 
membrane formation, and suggested lipoid solubility as the determining 
cause of efficiency. Both of these views assume, of course, that the 
acids to produce their effect must enter the cells. The ability of acids 
to change negatively heliotropic to positively heliotropic copepods 
seems to depend likewise on either their surface tension or their lipoid 
solubility. On the other hand there are certain effects of acids which 
TABLE 3. 
Absorption of 
Minimal cone. to} water by 
Toxicity Hemolysis of Toxicity for change neg. muscle. Per Efficiency in artificial 
to red blo seedlings of to pos. helio- |centincrease| parthenogenesis of sea- 
Parameecium.! corpuscles,? Lupinus albus.? tropism in inweightin1| urchin if butyric acid =1.° 
copepods. hour from 
n/110 cone. 
Form. ! 0.0005n Cl. 
Oxal. 0.0014” Form. 
n/6400 Trice. n/500 Caproic. | g (ac 3 Benz. 
n/4800  Salie. Val. 
a n/250 tee 8.6 SOx. <Nonylie (?) 
Lact. | 0.0037n Acet. 
Citr. Pr Monoc.}| n/200 Prop. 7.2 (Lac. 0.66 Prop. >Acetic (?) 
PO. | 0. 0065 n { op. Dic. 7.1 {Tric > For. (2) 
Caproic. Form Acet. | 69 |Oxal 
Cl Val SOs. For. 2 .33  Salic. 
0.0002 n {NOs | 0.0081 n (Boty. Tart. | 7/166 }NOs | 6.3 Tart. | (95 6 Oxy-butyric. 
fae: n/3200 — SOx. 5.6 Suce. ioe lack 
xo. : . ; 5 
Succ. et [Deke .06 Oxyisobutyric. 
pte 1 5‘ {Form. {Oxal. 
ycol. | Tart 
POs. 3.9 Acet. (?) ‘Sues. Dukythe 
oe {| Citr. eggs a ae 
Maleic. tain females 
Malon. 1/100 ee respond. 
Malic. 
n/1600 < Cit. Or. 
Val. 
Prop. 
|But. 
n/800 <Acet. 
Conc. which just kills in 7-30 min.; after Barratt, Zeit. f. alleg. Physiol., 4, p. 44], 
2Conc. which just causes hemolysis. Fihner u. Neubauer ,Arch. f. exp. Pathol. Ks 56, = 0333, 1907. 
4Conc. which just prevents growth. Kahlenberg and True, Bot. Gaz., 22, p. 81, 1896. 
4Loeb, Bioc. Zeit., 23, p. 95, oe 
5Loeb, Pfluger’s Archiv, 69, p. 1, 1897, and 71, p. 457, 1898. 
*Loeb, Bioc. Zeit., 15, p. 255, 1909. and Loeb, "Artificial Parthenogenesis and Fertilization, p. 143, 1913. 
seem to depend on the strength of the acid, for instance the hemolysis 
of blood corpuscles, if we can judge from the few results of Fiihner and 
Neubauer; also the absorption of water by muscle. In these pro- 
cesses capillary activity and lipoid solubility play a subordinate réle. 
Turning now to a comparison of the penetration rate into the tissues 
of the ‘prickly fish” with the physical properties of the acids we find 
again that there is no exact agreement in any case (table 2). Degree 
of dissociation is certainly not the determining factor in penetration, as 
a glance at the table will show. No one can deny but that there is a 
certain correspondence between lipoid solubility and capillary activity 
and penetration rate, yet it is far from exact. With acids as with so 
many other classes of substances it is only true in general that those 
1 Buty. <Caprylic (?) 
