Phenomena connected ivith Insect Metamotyliosis. 159 



Total, . . ^0392 



This experiment verified the first. I next treated the arti- 

 ficially prepared water used in experiment No. 2 with animal 

 charcoal. It was filtered through small lumps of pure animal 

 charcoal in an ordinary funnel, being passed through twice. 



On distillation the albuminoid ammonia was decreased from 

 •0224 gTS. per gal. to '004, the yield, however, still coming 

 over slowly. 



On treating the water contaminated with animal matter 

 in the same way, the ammonia was only decreased from '0392 

 to -0194 grs. per gal, the yield being principally in the first 

 distillate. 



The conclusion to be drawn'from these results is this : That 

 with a water contaminated with animal matter, the first and 

 second distillate of the albuminoid ammonia contain the prin- 

 cipal portion of the yield, whilst if the contamination be of a 

 vegetable nature, the ammonia is more evenly distributed 

 between the distillates. 



II. On certain Phenomena connected with Insect Metamor- 

 phosis. By T. D. GiBSOX Cakmichael, Esq. 



The two features in the metamorphosis of insects to which 

 the author draws attention are: (1.) the influence which 

 external conditions have on the form of insect larv«, and (2.) 

 the quiescence of the pupae of certain insects. In treating of 

 the first he shows how in an order so homogeneous as the 

 Hymenojytera in the perfect form a large amount of difference 

 prevails among the larvae, these being divisible into three 

 groups— (1.) the vermiform and apodal, (2.) those with slightly- 

 developed thoracic legs, and (3.) those with well-developed 

 thoracic legs, and abdominal prolegs. Such differences in the 

 larval forms of the same order he attributes to differences in the 

 habits of the grubs. The principal object of the author under 

 the first head is to draw attention to the influence of external 



