1883.] 



MICROSCOPICAL JOURNAL. 



the country, either for a walk, or to 

 collect objects for the microscope, to 

 carry a small wide-mouthed bottle 

 along, about half full of carbolic acid. 

 Into this we immediately drop any 

 minute insects we may find. The acid 

 kills them instantly, and in most cases 

 their legs are not found doubled be- 

 neath them, as in all other methods 

 of kjlling with which we are ac- 

 quainted. 



The acid used for this purpose, or 

 for mounting, should be the strongest 

 solution, — having just enough water 

 in it to keep it fluid at ordinary tem- 

 peratures. To use it for mounting, it 

 is only necessary to drop the specimen 

 into the acid, and in a few moments 

 transfer it to the prepared cell con- 

 taining the medium in which it is to 

 be mounted. Suppose it is desired to 

 mount a mosquito, or a plant-louse, or 

 any minute insect which requires no 

 preliminary treatment, drop the insect 

 into the acid, and in a few minutes it 

 will be seen that the fluid has thor- 

 oughly penetrated the body. Then it 

 is quite immaterial whether the speci- 

 men is to be mounted in water, or 

 glycerine, or balsam, for carbolic acid 

 will mix as readily with one as with 

 the other. Fill the cell with the me- 

 dium to be used ; place the specimen 

 on a clean slide, and take up the ex- 

 cess of fluid with blotting-paper ; then 

 transfer it to the cell and arrange the 

 parts with needles, when the cover- 

 glass can be applied. 



When deep cells are required for 

 balsam mounts, we are accustomed to 

 using brass curtain-rings, cemented to 

 the slide with shellac, or with hard 

 balsam. Shellac is preferable if as- 

 phalt varnish is to be used to finish 

 the mounts. After the cover is ap- 

 plied, the slide may be gently heated 

 until the outside balsam is hard enough 

 to keep the cover in place. Then the 

 excess of balsam can be cleaned off, 

 and a ring of shellac applied to pro- 

 tect the balsam, when the brass ring 

 may be concealed by any finishing 

 varnish. The same cells may he used 

 for glycerine or water mounts. 



Another way to make deep cells for 

 balsam is as follows : Build up a cell 

 of adequate depth for the object, by 

 successive layers of benzole-balsam, 

 and let this harden thoroughly. Then 

 fill it with soft balsam, and mount as 

 before. As a precaution against in- 

 jury to the cell, three pieces of thin 

 glass may be placed within it to sup- 

 port the cover. Such a cell can be 

 finished with damar varnish, and makes 

 a very attractive mount. 



When insects require any prelimin- 

 ary treatment to make them transpa- 

 rent, the soda solution should be 

 thoroughly removed by washing with 

 water ; after which the specimens 

 should be taken out one by one, the 

 superfluous water removed with blot- 

 ting-paper, and then thrown into the 

 carbolic acid. 



This method of mounting is the 

 simplest and best one we know of. 

 If the reader chooses to experiment 

 with it, let him take the head and pro- 

 boscis of a blow-fly, or any part of an 

 insect that may be available, and, with- 

 out any preliminary treatment, place 

 it in carbolic acid, and mount it in 

 balsam without pressure. A single 

 trial of this kind will convince him of 

 the ease with which excellent mounts 

 can be made ; and every one who tries 

 it will be a convert to the new method 

 of mounting without pressure. 



We have used carbolic acid instead 

 of alcohol in mounting stained sections 

 of wood, with excellent results, and it 

 is much cheaper than alcohol. % 



Starch. 



The structure of starch granules 

 has never been very fully made out, 

 although many observers have studied 

 the subject, and various views have 

 been put forward by different authors. 

 Among them the conclusions of Na- 

 geli seem to have received most gen- 

 eral acceptance ; although many have 

 never regarded them as entirely satis- 

 factory. There is great difficulty in 

 following the process of growth of 

 starch granules. We will not attempt 



