ClTTANE(nTS RESriRATION^. 
;!()('> 
Thermal comlitions also variously affect or intluonce tlie activity ot 
tlie res}»iratory function in ilifforent species, some species being more 
susceptible ami responsive to the tluctuations of temperature tlnin 
Fir,. .5nn. — Liin.'i.v ninximus L., with shield removed, to show the course traversed hy the 
respiratory air current (after Dr. T. Williams). 
The arrows show the general direction alTirmed to he followed hy the pure air at each inspiration. 
others. 'I’lie tluvi:itile Pulmonates do not, however, exclusively 
respire air, l)ut may at times he observed to regularly open and 
close their resi)iratory orifice when beneath the surface, more especially 
when the inhabited water de])arts from a medium temperature. 
Kumher of seconds per hour occupied in respiration. 
0 111 20 30 10 jO GO 70 80 00 100 110 
Fiii. (5)0. — Thermal-respiratory curves of Liinnaui L'nnnu’a auricularia and Pinn- 
ot his corncus, illustrating tlie varying degree in which changes of temperature ail'ect the rapidity 
of respiration in dilTereiit species. 
Nr)Ti’:. — 'File results indicated in tlie above diagram of the action of the respiratory organs show 
the average results of a large numher of ohservaiions upon individuals kejJt in conllnement, and 
it is jjossihle lli.it a more extended study under less arlificinl conditions will modify to some extent 
the results attained, as it may eliminate any elTects due to abnormality in the mollusks themselves 
or their surroundings. 
CrTANEOi's Resiuration i.s actively carried on through the general 
integument, e.specially hy the .slugs and other genera, and though 
usually subsidiary to that of the gills or lungs, yet, in some forms, 
as Auodoitfu, etc., the surface of the mantle may i)erform the func- 
tion of re.spiration even more effectually than the gills. 
Cutaneous re.siiiratinii in the Pulmonatc .species may, under certain 
c()nditions, he the chief mode of respiration, and i)ractically constitute 
