In use the chamber is first charged ?ifith a single animal confined in 20 

 microliters of medium. This isolation and determination of volume of the 

 medium can be effected most easily by making use of specially drawn micro- 

 pipettes, actuated by a mouthpiece similar to that of a hemocytometer 

 pipette. The loading pipette is calibrated to deliver 20 microliters. 

 This droplet is delivered onto one ivall of the respirometer chamber. The 

 chamber v/all is previously rendered hydrophobic by the application of a 

 silicone coating, such as "Dessicote" or "Nalcote." Under these conditions 

 the droplet of medium and its contained larva wiD.l retain its integrity 

 over long periods of time. It has, for example, frequently been possible 

 to make observations on a single larva during periods as long as tv/enty- 

 four hours. 



After the respirometer has been charged v;ith the animal and its medium, 

 a droplet containing ten microliters of alkali, either 10/j WaOH or 10,^ 

 Ba(GH)2, is placed on the contralateral virall, A droplet of highly purified 

 kerosene is placed in the capillary portion of tlie respirometerj the open 

 end of the respirometer is sealed with a non-oxidizing vfax. For best 

 adhesion and complete sealing it is preferable to employ a wax of low melt- 

 ing point. ..'ith the upper stopcock of the compensation chamber open the 

 two portions of the apparatus are unj.ted, seated and the joint is sealed 

 with the same wax iifhich was used to close the lower end of the respirometer. 

 The asoembly is then placed in the y/ater bath and permitted to come to 

 temperature equ.ilibrium. Empty respirometers generally reach a steady state 

 within thirty minutes. 



Our first concern was to determine the extent of the respiratory changes 

 which occur during normal development and maturation of free-swimming 

 larvae. Average results, secured from a study of ll5 larval Teredo are 

 shovm in Fig, 2, It vdll be observed that there is a real, and statisti- 

 cally significant, increase in oxygen consimption during the first twenty- 

 four hours of development. Thereafter for the remainder of the normally 

 infective, seventy-two hour period the rate of oxygen consumption drops 

 abruptly and steadily. It may be recalled that Isham and Tierney ( loc . cit . ) 

 denied larval T. pedicellata access to wood and found that after seventy- 

 two hours involutional changes Mere initiated v/hich terminated in death of 

 all such forms by the end of three hundred hours. Our respiratory data 

 supplement and confirm these observations. Mter seventy-two hours the 

 curve of ojcygen uptake shows a steady decline. It should also be recalled 

 that larval Teredo have not been observed to ingest solid food; thej are 

 provided with a finite glycogen store from the maternal organism. Decrease 

 in voluntary activity, in oxygen uptake and in glycogen content are all 

 related phenomena. 



A small series of ten 2U-hour larvae was studied in which the sea water 

 medium was made 0.001 M with glucose. These results are summarized in 

 Fig. 3. It will be observed that the addition of glucose to the medium 

 resulted in a li3/o increase in the rate of oxygen uptake. This must signify 

 that dissolved nutrient materials may be extracted from tl-e medium, even 

 though the ingestion of solid food has. not been observed. 



L - 3 



