56 



THE AMERICAN MONTHLY 



[March, 



glass with shellac, it is sometimes 

 done with hard Canada balsam dis- 

 solved in benzole. This is an excel- 

 lent plan when the preservative fluid 

 is water or an aqueous solution of 

 some chemical substance. However, 

 usually shellac alone is sufificient. 



As to the operations of mounting, 

 very little practice is necessary. The 

 time required is reduced to a mini- 

 mum if all the apparatus required is 

 placed in a single box, and kept ready 

 for instant use. We have followed 

 this plan for years, and whenever we 

 are looking over a collection from a 

 stream or pond and find a rare or 

 especially interesting specimen that 

 we wish to preserve, we have merely 

 to take down our mounting-box and 

 turn-table, and, without losing a min- 

 ute of time, proceed with the mount- 

 ing. 



Finding, for instance, a species of 

 algse, we select a slide having a ring 

 of shellac previously prepared upon 

 it, and place it on the turn-table. 

 Then a fresh coat of shellac is added 

 and a drop of preservative placed in 

 the center. The alga is then trans- 

 ferred to the slide and the cover-glass 

 immediately applied and pressed 

 down around the edges, the superflu- 

 ous moisture wiped off, and the cover 

 sealed down by another coat of ce- 

 ment. The slide is then ready to be 

 put away until a convenient time for 

 finishing it with the asphalt and gold- 

 size. 



Mounting in balsam is also a sim- 

 ple operation, and has been fully de- 

 scribedinthis Journal(Vo1. I, p.i6i). 



We trust the suggestions of this ar- 

 ticle will not be lost sight of by pro- 

 fessional men. Five or ten minutes 

 occasionally devoted to the mounting 

 of specimens may result in great satis- 

 faction afterward. 



The Cause of Diphtheria. — Sup- 

 plement No. 17, of the National Board 

 of Health Bulletin, contains the full 

 report of the studies of Drs. H. C. 

 Wood and H. F. Formad, conducted 

 during the years 1880 and 1881. The 



" Bibliographical Introduction " gives 

 a number of references to important 

 articles written both in favor of and 

 opposed to, the idea of a fungoid 

 origin of this disease. The second 

 chapter relates to studies upon the 

 human subject. It is here affirmed 

 that the micrococci of diphtheria can- 

 not be distinguished by microscopi- 

 cal examination from such as are 

 found in cases of ordinary throat in- 

 flammation, or furred tongue. To de- 

 termine whether micrococci are al- 

 ways present in diphtheria, a large 

 number of cases were examined, em- 

 bracing those of a mild and of a ma- 

 lignant nature. In the mild form of 

 the disease, and even in the less se-. 

 vere cases of the malignant type, 

 micrococci are usually not found in 

 the blood; but in the severe cases 

 the blood always contains them. It 

 is possible, however, that the micro- 

 cocci find their way into the blood 

 through the lymphatics, and they 

 may not have time, therefore, to enter 

 the blood before death ensues. 

 This supposition is strengthened by 

 the fact that they have been observed 

 to appear in the blood some hours 

 after death; but more direct evidence 

 on this point is still wanting. Micro- 

 cocci have been sought for in the 

 blood of persons suffering from other 

 diseases, but they have only been 

 found by the authors in three cases, 

 and even these may have been of a 

 diphtheritic nature. 



The third chapter treats of the 

 pathology of diphtheria. It opens 

 with a direct contradiction of the 

 opinion quite generally held, that 

 diphtheria and pseudo-membranous 

 croup are distinct diseases, and the 

 reasons for the position thus assumed 

 are clearly stated. 



The micrococci found in the diph- 

 theritic false membrane are always of 

 two sizes, probably representing dif- 

 ferent stages of development. The 

 smaller usually infest the leucocytes, 

 while the others form zoogloea- 

 masses, infesting or destroying the 

 epithelial cells. The number of mi- 



