THE OOLOGIST. 



151 



fjreater variety, the latter is taken to a 

 large extent. Of tlie animal food, 

 three per cent, consists of wild bees 

 and carniverous wasps which assist 

 nature by carrying pollen from one 

 plant to another, but this is counter- 

 balanced by the destruction of the 

 thousand legs, plant feeding bugs and 

 weevi's. 



The easily procured predaceous 

 ground beetles, are also a favorite as 

 has been mentioned, but even the de- 

 struction of these beneficial beetles 

 is compensated for by the number of 

 the May beetles and their relatives 

 which are destroyed. These added to 

 the caterpillars, crickets, grasshoppers, 

 leaf eating lice and click beetlo'-i, make 

 our friend Oaleoscopies carolinejisis, 

 clearly beneficial to the husbandman 

 and as such he deserves their protection 

 and care, rather than the persecution, 

 to which however he is all too often 

 subjected. The next paper will deal 

 with the gastronomic proclivities of the 

 House Wren. 



Pancreatin vs Caustic Potash. 



While I dislike entering into a con- 

 troversy over this matter, I believe it is 

 due the readers of this magazine that 

 someone should compare the prop- 

 erties and merits of these com- 

 pounds, as a knowledge of them may 

 be the means of saving rare and valu- 

 able specimens which might otherwise 

 be destroyed after having been taken 

 from the birds. 



When I wrote the item "Don't Use 

 Caustic Potash" (Oologist May 1899) it 

 was with the purpose of adding some- 

 thing to the technique of preparing 

 odlogical specimens. I have usd both 

 the pancreatin and potash during my 

 eighteen years of oological collecting 

 and after a careful comparison I am 

 more in favor of using pancreatin for 

 removing embryos than I ever was. 



Let us compare the two compounds- 

 Caustic potash [Potassa, Potassium Hy- 

 drate] is a very powerful and active 

 alkah, which when brought in contact 

 with other compounds, decomposes 

 them, extracting their water ard upset- 

 ting their chemical equilibrium When 

 a drop of the potash solution touches the 

 shell of a delicatelv tinted or ppot'ed 

 6gg it decolorizes it wherevor the so- 

 lution touches. Having a decide'^ pro- 

 pensity for combining with other alka- 

 lies thn pota'h decomposes the calcium 

 salts of which the egg thell is rompos- 

 ed, changing them from carbonates, 

 etc.. to the hydrate and thereby render- 

 ing the shell very brittle and so d s- 

 arranging and changing the composi- 

 tion of the egg shell, that it is not egg 

 shell at all but merely a comj)orcnd made 

 from egg shdl. Potash saponifies the 

 embryonic contents cf the egg and this 

 soap is so alkaline that the whole in- 

 side of the egg shell is attacked by its 

 corrosive and caustic properti s and the 

 shell is charred and weakened even if 

 none of the solution touches the outside 

 of the egg. The potash solution also at. 

 tacks the skin on the hands of th-i oper 

 ator and for that reason is disagreeable 

 to handle. 



In 1895 I took a set of eleven pggs of 

 Blue-winged Teal which were advanced 

 in incubation. Having no pancreatin 

 I used caustic potash (which I had at 

 hand) to help remove the embryos. 

 The eggs are in my cabinet now but 

 they are bleached on the outside and 

 stained with dingy black on the inside, 

 by the chemical decomposition brought 

 abont by the potash and are examples 

 of what is claimed against the alkali. 



Pancreatin is an organic ferment 

 which digests albumenoidf, converts 

 starch into sugar, emulsities fats and 

 curdles milk. It is not sufficiently 

 alkaline (or acid) to combine readily 

 with the salts composing the egg shell 

 consequently does not change or de- 

 compose them. Being a ferment it di- 



