112 



SCIENCE 



[N. S. Vol. XLVI. No. 1179 



pulse at ^ as at D; for the rise of pressure de- 

 termined by the addition of a given volume of in- 

 compressible material to a confined gas-filled space 

 is proportional to the pressure of the gas filling the 

 space. 



This statement is also expressed in the dia- 

 gram^ which is here given in photographic 

 reproduction. The beginning pressure is 

 marked zero — i. e., ignoring barometric pres- 

 sure — ^the " diastolic pressure " marked on the 

 ordinate is just half way between zero and the 

 " systolic pressure." The ordinates drawn to 

 represent the extent of oscillations are in the 

 same ratio, that is the " systolic rise" — EY' — 

 at double the manometer pressure is just 

 twice that marked at N near DY for diastolic 

 pressure — a ratio of 1:2. 



Boyle's Law shows that the ratio would be 

 P/P where P is the original total pressure; 

 P' the new pressure produced by the addition 

 of a constant volume of fluid. Accordingly: 

 introducing Y and Y' as the respective vol- 

 umes of the gas with K as the constant it was 

 found in a concrete case where Y was 100 c.c. 

 and where 1 c.c. of fluid was added with the 

 barometer at Y47 mm. that the ratio of the 

 size of the oscillations at 50 mm. (manometer) 

 beginning pressure as compared with 100 nam. 

 (797 mm. and 847 mm. total pressure) was 

 8.05 : 8.55 or 1 : 1.06 plus instead of 1 : 2 as per 

 Erlanger hypothesis. 



The ratio at mm. (manometer) beginning 

 pressure as compared with 100 mm. (manom- 

 eter pressure was 7.54:8.55 or 1:1.13 in- 

 stead of 1: infinity as demanded by the Er- 

 langer hypothesis. 



A. M. Bleile 



Ohio State TJniveesitt, 

 Columbus 



faunal conditions in south georgia 

 Regarding Mr. Luke's note on the rats of 

 South Georgia,^ it may be of interest to record 

 that his question as to " what characteristics 

 the rat would develop after a few years of such 

 a specialized habitat " has been at least pro- 

 visionally answered by the Swedish zoologist, 

 Dr. Einar Lonnberg. This author in 1906 

 described the South Georgia rat as a new sub- 



3 Loc. cit., 407. 



1 Science, N. S., XLV., 502, 503, 1917. 



species,' and noted that it apparently differed 

 from the typical brovm rat in having a 

 thicker skin, denser and longer fui, and a 

 more rusty color. 



Several of Mr. Luke's observations would 

 be hard to substantiate, for instance the state- . 

 ment: 



Until about thirty years ago there were no rats 

 on the islands. 



It is much more probable that these ubi- 

 quitous rodents were introduced in sealing 

 vessels not long after American and British 

 sealers first began to exploit South Georgia 

 on a large scale, which was in the year 1800. 

 Klutschak, who visited South Georgia in 

 1877, transcribed and published an American 

 sealer's chart of the island, and designated 

 as " Rattenhafen " ^ the bay known to modern 

 Norwegian whalemen as " Prince Olaf Har- 

 bor," but called "Port Gladstone" on the 

 latest British map. Rats are still exceedingly 

 abundant about this inlet, as I foimd in 1913. 

 Within recent years rats are known to have 

 been reintroduced repeatedly at Cumberland 

 Bay. 



The rats at South Georgia can not fairly 

 be accused of having " devastated the few 

 small animals living on the island," unless the 

 birds are meant; there are no other native 

 land vertebrates. Rabbits were introduced 

 about 1872 by a sealer coming from Tristan 

 da Cunha, and perhaps two or three times 

 since, but they never gained a foothold. A 

 few horses and reindeer have been thriving 

 there in a feral state for a number of years. 



The whaling industry was started at South 

 Georgia not " a few decades ago," but in 1904. 

 Although the rats do feed upon the whale 

 carcasses, as Mr. Luke writes, it would be a 

 mistake to suppose that they are at all de- 

 pendent upon this source of food, for the 

 creatures appear to be very nearly as abun- 

 dant about the uninhabited fiords as they are 

 along the shores of the carcass-strewn bays. 

 I observed at Possession Bay, the Bay of Isles, 

 and elsewhere, that the rats eat the young 



2 Kungl. Sv. Vet. ATcad. Eandlingar., Bd. 40, No. 

 5, 21-23, 1906. 



3 Deutsch. Bundschau f. Geogr. u. Stat., Bd. III., 

 522-531, 1881. 



