^7(; STATE BOARD OF AGRICULTURlO. 



(The very poor penctratiug power of osmic acid fumes, when used as a 

 histological killing agent, are well known.) It may only be suggested 

 here that perhaps the first effect of osmic acid fumes in blackening lipoids 

 and fats in the experiment-membrane (or the surface of a living grass- 

 hopper, etc.) is to establish a black surface-membrane at once which is 

 not only a little less permeable to oxygen, but also much less permeable 

 to the osmic acid fumes, themselves. 



THE EFFECT OF TEMPERATURE ON THE CAPACITY OF LIVING INSECT 



TISSUES FOR THE ABSORPTION OF CERTAIN 



GASES OR VAPORS. 



In Table VI results are given of gasoline-vapor absorptions by 3-gram 

 samples of egg-albumen, and also by the same amounts, respectively, of 

 fresh unincubated egg-yolk and of fertile egg-j^olk after four and five 

 days of incubation. It was a surprise, in these tests, to find that gas- 

 oline vapor was about six times more soluble in egg-albumen than in the 

 fresh egg-yolk, although the latter contained fats and fat-like material 

 in the greater amounts by far. All other tests, so far carried out, had 

 shown fats and lecithin to have greater capacity for the absorption of 

 gasoline-vapor than egg-albumen. The exception, therefore, seemed so 

 interesting and so possibly significant that it Avas decided to test the 

 absorption capacity of the J'olk for gasoline-vapor after certain periods 

 of incubation. The yolk of infertile eggs, even after several days of 

 incubation, was found to give the same results as yolk taken from fresh 

 unincubated eggs. In the case of incubated fertile eggs the young, de- 

 veloping embryo was stirred up with the yolk before the 3-gram sample 

 for the absorption test was taken. A comparison of such results of yolk- 

 absorptions as are given in Nos. 2 and 3 with those given in Nos. 5 and G 

 of Table VI seemed to show that the solubility, for gasoline-vapor, of fats 

 and lipoids in the yolk changed greatly in the four and five days of incu- 

 bation. The first few hours of incubation did not bring about a measur- 

 able change in the capacity of the yolk to dissolve gasoline-vapor. All 

 the tests with yolk samples as given in the table were made at a room 

 temperature of 25° to 26° C. Four tests with yolk samples of only a few 

 hours incubation were made in a small incubation room at 103° F. 

 These gave practically the same results, as to absorption capacity, as 

 similar tests at the ordinarj' room temperature; if there was any in- 

 crease in that capacity, it was not great enough to measure. As is well 

 known, on about the fourth and fifth days of incubation the embryo of 

 the hen's egg begins to show quite decided respiratory activity, and a 

 period of rapid development begins. It was at this period of incubation 

 that the decided increase in the capacity for absorbing gasoline vapor 

 was shown by the embryo-j'olk-mixture.* Here was an interesting change, 

 (an increase) in the absorption capacity of the yolk-mixture for gasoline 

 vapor, which seemed to be related with the changes that made for active 

 development in the embryo. As long as the embryo remained compar- 

 atively dormant (or, was unable to develop through non-fertilization, 



♦Attention should be called to the fact that absorption results In 5 and 6 are much greater 

 than the absorptions given by egg-albumen (1. e. egg-white). It would seem that the change 

 in the embryo-yolk-mixture, which occasioned an increase in the gasoline-vapor absorptions, 

 was probably a change in the fats and lipoids. The amount of alcohol-soluble material In 

 the embryo is said to increase rapidly with development. 



