OBSERVATIONS ON INCUBATION. 343 



matter that of a hyaloid transparent substance without cells. The fluid was 

 coagulated by heat. The air collected from one of them consisted of 40 per cent, 

 carbonic acid, 2 oxygen, 58 azote. 



No contrast could be greater than the appearance and state of the unimpreg- 

 nated eggs in these two trials ; in the first, with the exception of No. 3, so little 

 changed, in the last so much changed, so much so as to be suggestive of the death 

 of the eggs, the formation of mucedo, and of its death and decomposition, the 

 colouring matter remaining. 



II. Of Eggs kept at a Temperature of about 32° Fahr. 



On the 24th of June, four newly laid eggs were put into an ice-house, where 

 they were left until the 19th of July. Cracks were found in two of them when 

 taken out, but without any exudation of contents. These cracks might denote the 

 freezing of the eggs. Put under a hen on the evening of the 17th, with nine fresh 

 eggs, the latter were hatched on the 10th of August, as was also one of the former ; 

 the two cracked eggs were crushed. The fourth from the ice-house, when broken 

 was found to contain a mixture of yolk and white in the form of emulsion, with 

 some unmixed yolk in a thickened state. The contents had an unpleasant smell, 

 as if from incipient putrefaction. 



III. Of Eggs subjected to the Air-Ptcmp. 



1. On the 14th of April six newly laid eggs were thus treated until the 23d. 

 The air-pump was in good order, and it was worked twice or thrice daily. On 

 the 23d, these eggs were put under a hen with seven newly laid ones. The hatch- 

 ing began on the 13th of May ; on the 14th all were hatched with the exception 

 of one, — one of those subjected to the air-pump : this egg swam in water ; had, 

 when broken, an unpleasant smell, denoting incipient putrefaction ; and the white 

 and part of the yolk were mixed, forming a yellow opaque emulsion. There was 

 an obscure appearance of an embryo in that portion of the yolk which was re- 

 tained in its membrane. The newly laid eggs were hatched a few hours earlier 

 than those acted on by the air-pump. 



2. Three newly laid eggs, on the 28th of May, weighed as follows : — 



No. 1 weighed 874-8 grs. i No. 3 weighed 953-0 grs. 

 2 ... 912-0 „ 



They were subjected to the air-pump until the 2d of June, when, on weighing, 

 they were found to have sustained the following loss : — 



No. 1, ... 4-8 grs. I No. 3, ... 5-1 grs. 

 2, ... 4-0 „ 



They were put into water, and again subjected to the air-pump, which was worked 



