116 DR DAVY'S OBSERVATIONS ON THE CUTICLE 



feathers, and without the thigh (No. 2), weighed 426. The integuments were 

 left on, and to prevent access to the muscles and the deposition of the ova of the 

 flesh-fly, sufficient skin from the thigh was drawn over the stump and secured 

 from ingress by a ligature of fine silk. 



July 28. No. 1 had lost 22-2 grs., or 44-3 per cent. 



„ „ „ 2 „ 2-7 „ 60 „ 



„ 29. „ 1 „ 31-6 „ 63-0 „ 



„ » „ 2 „ 45 „ 100 „ 



„ 31. „ I „ 334 „ 66-6 „ 



„ „ „ 2 „ 6-75 „ 158 „ 



Aug. 4. „ 1 „ 33-55 „ 66-9 „ No further loss. 



„ „ » 2 „ 14-6 „ 34-0 „ 



7. „ 2 „ 21-6 „ 50-0 „ 



„ 10. „ 2 „ 25-2 „ 591 „ 



In both instances, in the dried state to which they were reduced, little change 

 had taken place. Even when examined now, after eight months, the muscles are 

 found to retain their striated structure. In the instance of No. 2, this was pro- 

 bably owing to the pretty rapid drying from the small bulk of the limb. 



12. I will mention one example more, a trial made in winter, between January 

 the 4th and March the 14th, in a room the temperature of which seldom exceeded 

 50°. The Blue Tit (Parus coeruleus) was the subject of the experiments. One. 

 deprived of its skin (No. 1), weighed 169 grs. ; another (No. 2), deprived merely of 

 its feathers, weighed 122-3 grs. Without giving the details of the weighing at short 

 intervals, it may suffice to state that No. 1 had lost in twenty-six days 105 grs.. 

 or 62 per cent. ; whilst No. 2 had lost 51 - 4 grs., or only 37 per cent. The first 

 had become quite rigid and hard, and sustained no further loss ; the second con- 

 tinued to lose weight, but so very slowly, that on the 14th March it was not 

 thoroughly desiccated. It had lost 83*1 grs., or 60 per cent. 



Whilst the results which have been described sufficiently show the powerful 

 influence of the integuments in moderating evaporation, if we compare those 

 obtained in the experiments on different animals a marked difference is notable. 

 The moderating or retentive power of the integuments of the frog and toad is 

 seen to be lowest, that of the trout next, that of the mammalia higher, and that 

 of birds highest. 



In the instance of the common fowl the thigh showed a much more retentive 

 power than that of the wattle ; and it can hardly be doubted that were trials 

 made of different parts of any other animal, a variety of moderating influences 

 would be witnessed, according to the degree of thickness of the covering and 

 difference of physical structure. 



As the cuticle is considered anorganic, may not the part it performs in rela- 

 tion to the checking of evaporation in the living body be held to be much the 

 same as in the dead body ? 



