THE AMERICAN MONTHLY 



[January, 



absorption of food into the general 

 system. 



In regard to the respiration, he 

 showed how the water entered the 

 gills, and by a series of innumerable 

 millions of little lashes in action, like 

 oars, carried the water through the 

 minutest part of the gills, eliminat- 

 ing the oxygen from the contained 

 air. In res^Dect to the circulation, he 

 showed the heart in pulsation, com- 

 posed of the ventricle and auricle, the 

 latter receiving the aerated blood from 

 the gills, giving the same to the ven- 

 tricle, which by two aortas distributed 

 the blood through the entire surface 

 of the animal. He spoke of the oys- 

 ter as having some capacity for educa- 

 tion, in that it can adjust itself to many 

 new environments ; and then went on 

 to describe the building up the oyster's 

 house, — its shells. He told how the 

 shells were formed, and how the age 

 of an oyster can be told by the layers 

 of the shells, by the hinge-lines, and 

 by the position of the adductor muscle. 

 He then described the companions of 

 the oyster and their habits ; detailing 

 their efforts in gathering food for the 

 mollusc ; and also the enemies of the 

 oyster, such as the drum fish, that 

 grinds them up, destroying millions of 

 them in a night ; of the drill, that bores 

 a hole through the shell and then sucks 

 out the life and body, unless the oyster 

 defeats the attack by plugging up the 

 hole. The sea-star and the conch 

 were added to the list of enemies, each 

 one's operatfons being minutely de- 

 scribed. 



Carbolic Acid in Mounting. 



BY WM. J. POW. 



In our last number there appeared 

 an article on the subject of mounting 

 without pressure, taken from an Eng- 

 lish periodical. In that article the 

 advantages of the method described 

 were well set forth, and no reader can 

 fail to appreciate the value of any pro- 

 cess which enables us to remove the 

 air from an object without drying it, 



and causing it to become hard, and 

 readily injured by handling. The 

 method there described is an excellent 

 one when the insect to be mounted is 

 opaque, and of considerable size. The 

 use of the soda-solution is to make 

 the opaque portions transparent, and 

 it softens the hard parts. 



There are many insects which do 

 not require the use of the solution of 

 soda, and even among those that do 

 require it to render them quite trans- 

 parent, may still make beautiful ob- 

 jects when mounted in balsam by the 

 method to be described in this article. 

 For ourselves, we do not like to use 

 alcohol in mounting insects, because 

 it hardens the parts, making them stiff, 

 and not as readily arranged as may be 

 desired. In the case of vegetable tis- 

 sues, it is sometimes objectionable for 

 the same reason. An excellent sub- 

 stitute for alcohol, and one that can be 

 almost universally used in its stead in 

 mounting, is carbolic acid. Contrary 

 to the general opinion, carbolic acid 

 is not an acid, and the name is mis- 

 leading. It has no acid properties 

 whatever. Chemically speaking it is 

 an alcohol, belonging to a series of alco- 

 hols quite ditferent in composition from 

 common ethyl alcohol, which we use, 

 and from wood spirit, which is closely 

 related to common alcohol. But car- 

 bolic acid is, nevertheless, a true al- 

 cohol, and for this reason it can be 

 frequently substituted, for ethyl alco- 

 hol is microscopical work. But what 

 advantages has it over the latter ? One 

 great advantage is found in the readi- 

 ness with which it penetrates a speci- 

 men, and mixes with the fluids used 

 in mounting, such as water, glycerine 

 and Canada balsam. Another is, that 

 it does not harden tissues and make 

 them stiff. For this reason insects, or 

 parts of insects, can be preserved in- 

 definitely in carbolic acid, in a fit con- 

 dition to be mounted at any time. 

 The more delicate parts are made 

 quite transparent by long soaking in 

 the solution ; but this is no detriment 

 to them. 



It is our custom, when going out in 



